Attitude quotes

'Where Do We Go From Here?" as published in Where Do We Go from Here : Chaos or Community? (1967), p. 62; many statements in this book, or slight variants of them, were also part of his address Where Do We Go From Here?" which has a section below. A common variant appearing at least as early as 1968 has "Returning violence for violence multiplies violence..." An early version of the speech as published in A Martin Luther King Treasury (1964), p. 173, has : "Returning hate for hate multiplies hate..."
1960s
Source: A Testament of Hope: The Essential Writings and Speeches
Context: The ultimate weakness of violence is that it is a descending spiral, begetting the very thing it seeks to destroy. Instead of diminishing evil, it multiplies it. Through violence you may murder the liar, but you cannot murder the lie, nor establish the truth. Through violence you may murder the hater, but you do not murder hate. In fact, violence merely increases hate. So it goes. … Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars. Darkness cannot drive out darkness: only light can do that. Hate cannot drive out hate: only love can do that.

Variant: Imperfection is beauty, madness is genius and it's better to be absolutely ridiculous than absolutely boring.

As quoted in Journal of France and Germany (1942–1944) by Gilbert Fowler White, in excerpt published in Living with Nature's Extremes: The Life of Gilbert Fowler White (2006) by Robert E. Hinshaw, p. 62. From the context http://books.google.com/books?id=_2qfZRp9SeEC&lpg=PP1&pg=PA62#v=onepage&q&f=false it seems that White did not specify whether he had heard Einstein himself say this or whether he was repeating a quote that had been passed along by someone else, so without a primary source the validity of this quote should be considered questionable.
Some have argued that elsewhere Einstein defined a "miracle" as a type of event he did not believe was possible—Einstein on Religion by Max Jammer (1999) quotes on p. 89 from a 1931 conversation Einstein had with David Reichinstein, where Reichinstein brought up philosopher Arthur Liebert's argument that the indeterminism of quantum mechanics might allow for the possibility of miracles, and Einstein replied that Liebert's argument dealt "with a domain in which lawful rationality [determinism] does not exist. A 'miracle,' however, is an exception from lawfulness; hence, there where lawfulness does not exist, also its exception, i.e., a miracle, cannot exist." ("Dort, wo eine Gesetzmässigkeit nicht vorhanden ist, kann auch ihre Ausnahme, d.h. ein Wunder, nicht existieren." D. Reichenstein, Die Religion der Gebildeten (1941), p. 21). However, it is clear from the context that Einstein was stating only that miracles cannot exist in a domain (quantum mechanics) where lawful rationality does not exist. He did not claim that miracles could never exist in any domain. Indeed, Einstein clearly believed, as seen in many quotations above, that the universe was comprehensible and rational, but he also described this characteristic of the universe as a "miracle". In another example, he is quoted as claiming belief in a God, "Who reveals Himself in the lawful harmony of the world."
As quoted in From Yale to Jail: The Life Story of a Moral Dissenter (1993) by David T. Dellinger, p. 418
Disputed
Variant: There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.
Variant: There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.

1979

Variant: Some people want it to happen, some wish it would happen, and others make it happen.

We Bereaved (1929)

2021

Lord Darlington, Act III
Source: Lady Windermere's Fan (1892)

Attributed quotes

Variant: Today is your day, your mountain is waiting. So get on your way.

Foreword (January 1960)
You Learn by Living (1960)

Source: Man's Search for Meaning

Variant: When fate hands you lemons, make lemonade.

Source: An Ideal Husband

Attributed to Winston Churchill in The Prodigal Project : Book I : Genesis (2003) by Ken Abraham and Daniel Hart, p. 224 and other places, though no source attribution is given. It actually derives from an advertising campaign for Budweiser beer in the late 1930s.
Misattributed
Variant: Success is not final, failure is not fatal: it is the courage to continue that counts.
Source: http://quoteinvestigator.com/2013/09/03/success-final/

Source: Hamlet, Act II, scene ii.

This has become attributed to both Walt Whitman and Helen Keller, but has not been found in either of their published works, and variations of the quote are listed as a proverb commonly used in both the US and Canada in A Dictionary of American Proverbs (1992), edited by Wolfgang Mieder, Kelsie B. Harder and Stewart A. Kingsbury.
Misattributed

Source: Man's Search for Meaning

Actually said by Napoleon Hill, Stone later added the line "...with P.M.A." (Positive Mental Attitude) to the end of this quote.
Misattributed
Variant: Whatever the mind of man can conceive and believe, it can achieve.

Source: The Secret Garden

Source: Brideshead Revisited: The Sacred and Profane Memories of Captain Charles Ryder

Anonymous American proverb; since 1998 this has often been attributed to Mark Twain on the internet, but no contemporary evidence of him ever using it has been located.
Variants:
It is not the size of the dog in the fight that counts, but the fight in the dog that matters.
"Stub Ends of Thoughts" by Arthur G. Lewis, a collection of sayings, in Book of the Royal Blue Vol. 14, No. 7 (April 1911), cited as the earliest known occurrence in The Dictionary of Modern Proverbs, edited by Charles Clay Doyle, Wolfgang Mieder, and Fred R. Shapiro, p. 232
It is not the size of the dog in the fight that counts, but the fight in the dog that wins.
Anonymous quote in the evening edition of the East Oregonian (20 April 1911)
What counts is not necessarily the size of the dog in the fight — it's the size of the fight in the dog.
Dwight D. Eisenhower, declaring his particular variant on the proverbial assertion in Remarks at Republican National Committee Breakfast (31 January 1958) http://www.presidency.ucsb.edu/ws/index.php?pid=11229
Misattributed

Disputed
Variant: No one can make you feel inferior without your permission.
Source: Sometimes claimed to appear in her book This is My Story, but in The Quote Verifier by Ralph Keyes (2006), Keyes writes on p. 97 that "Bartlett's and other sources say her famous quotation can be found in This is My Story, Roosevelt's 1937 autobiography. It can't. Quotographer Rosalie Maggio scoured that book and many others by and about Roosevelt in search of this line, without success. In their own extensive searching, archivists at the Franklin D. Roosevelt Library in Hyde Park, New York, have not been able to find the quotation in This Is My Story or any other writing by the First Lady. A discussion of some of the earliest known attributions of this quote to Roosevelt, which may be a paraphrase from an interview, can be found in this entry from Quote Investigator http://quoteinvestigator.com/2011/03/30/not-inferior/.

In the House of Commons, February 28, 1906 speech South African native races http://hansard.millbanksystems.com/commons/1906/feb/28/south-african-native-races#S4V0152P0_19060228_HOC_307
The Second World War (1939–1945)
Variant: Where there is great power there is great responsibility
Context: I submit respectfully to the House as a general principle that our responsibility in this matter is directly proportionate to our power. Where there is great power there is great responsibility, where there is less power there is less responsibility, and where there is no power there can, I think, be no responsibility.

Lord Darlington, Act I
Variant: I can resist everything except temptation
Source: Lady Windermere's Fan (1892)

The Diary of a Young Girl

Remarks at Republican National Committee Breakfast (31 January 1958) http://www.presidency.ucsb.edu/ws/index.php?pid=11229; Eisenhower hear delivers his particular variation of a pre-existing proverb, which has since become widely dispersed as simply "It's not the size of the dog in the fight; it's the size of the fight in the dog." In that form it has become widely attributed to Mark Twain on the internet, as early as 1998, but no contemporary evidence of Twain ever using it has been located. The earliest known variants of it occur in 1911, one in a collection of sayings "Stub Ends of Thoughts" by Arthur G. Lewis, in Book of the Royal Blue Vol. 14, No. 7 (April 1911): "It is not the size of the dog in the fight that counts, but the fight in the dog that matters", as cited in The Dictionary of Modern Proverbs, edited by Charles Clay Doyle, Wolfgang Mieder, and Fred R. Shapiro, p. 232, and the other as "It is not the size of the dog in the fight that counts, but the fight in the dog that wins" in the evening edition of the East Oregonian (20 April 1911) http://listserv.linguistlist.org/pipermail/ads-l/2015-October/139250.html
1950s

A Fish Dinner in Memison (1941)
Context: The black arrowed swoop of the moment swung high into the unceilinged future, ten, fifty, sixty years, may be: then, past seeing, up to that warmthless unconsidered mock-time, when nothing shall be left but the memorial that fits all (except, if there be, the most unhappiest) of human kind: I was not, I lived and loved, I am not.

Anonymous advertising copywriter for Menards chain of hardware stores (2000), according to Quote Investigator http://quoteinvestigator.com/2014/01/20/be-yourself
Misattributed

Source: Thief of Time

Letter to Isham Reavis (5 November 1855)
1850s
Context: If you are resolutely determined to make a lawyer of yourself, the thing is more than half done already. It is but a small matter whether you read with anyone or not. I did not read with anyone. Get the books, and read and study them till you understand them in their principal features; and that is the main thing. It is of no consequence to be in a large town while you are reading. I read at New Salem, which never had three hundred people living in it. The books, and your capacity for understanding them, are just the same in all places.... Always bear in mind that your own resolution to succeed, is more important than any other one thing.

Source: Think and Grow Rich

Source: Eragon, Eldest & Brisingr

Source: Life's Little Instruction Book

p.32 -->
Variant: Whatever the mind of man can conceive and believe, it can achieve.
Source: Think and Grow Rich: A Black Choice

Source: Hell's Angels: A Strange and Terrible Saga

Variant: Your attitude, not your aptitude, will determine your altitude.

Source: Meditations

As quoted in Secrets of Superstar Speakers: Wisdom from the Greatest Motivators of Our Time (2000) by Lilly Walters, p. 96

Ibid.
The Book of Disquiet
Original: Isso não é o meu amor; é apenas a sua vida.

Source: Striking Thoughts (2000), p. 120

Introduction (1966)
Sometimes misquoted as: Be careful what you pretend to be because you are what you pretend to be.
Mother Night (1961)

Attributed

Dag Redwing hickory Bluefield

Passage (Vol. III in Tetralogy) (2008), p. 163
The Sharing Knife, Passage (Vol. III in Tetralogy) (2008)

Source: The Greening of America (1970), Chapter I : The Coming American Revolution, p. 4
Context: There is a revolution coming. It will not be like revolutions of the past. It will originate with the individual and with culture, and it will change the political structure only as its final act. It will not require violence to succeed, and it cannot be successfully resisted by violence. It is now spreading with amazing rapidity, and already our laws, institutions and social structure are changing in consequence. It promises a higher reason, a more human community, and a new and liberated individual. Its ultimate creation will be a new and enduring wholeness and beauty — a renewed relationship of man to himself, to other men, to society, to nature, and to the land.
This is the revolution of the new generation.

Introduction
The Log from the Sea of Cortez (1951)
Context: "... Let us go," we said, "into the Sea of Cortez, realizing that we become forever a part of it; that our rubber boots slogging through a flat of eel-grass, that the rocks we turn over in a tide pool, make us truly and permanently a factor in the ecology of the region. We shall take something away from it, but we shall leave something too." And if we seem a small factor in a huge pattern, nevertheless it is of relative importance. We take a tiny colony of soft corals from a rock in a little water world. And that isn't terribly important to the tide pool. Fifty miles away the Japanese shrimp boats are dredging with overlapping scoops, bringing up tons of shrimps, rapidly destroying the species so that it may never come back, and with the species destroying the ecological balance of the whole region. That isn't very important in the world. And thousands of miles away the great bombs are falling and the stars are not moved thereby. None of it is important or all of it is.

That frightens all the childish
And extinguishes fear in the wise.

§ 26
Major attributed works, Ratnāvalī (Precious Garland)

Original: ​(it) L'occasione della tua vita, sei tu.
Source: prevale.net

Speech made in honor of Thomas Mann in January 1939, when Mann was given the Einstein Prize given by the Jewish Forum. Quoted in Einstein Lived Here by Abraham Pais (1994), p. 214 http://books.google.com/books?id=u_9QAAAAMAAJ&q=%22becomes+lack+of+power%22#search_anchor
1930s
Context: The standard bearers have grown weak in the defense of their priceless heritage, and the powers of darkness have been strengthened thereby. Weakness of attitude becomes weakness of character; it becomes lack of power to act with courage proportionate to danger. All this must lead to the destruction of our intellectual life unless the danger summons up strong personalities able to fill the lukewarm and discouraged with new strength and resolution.

Variant: It isn't what you have, or who you are, or where you are, or what you are doing that makes you happy or unhappy. It is what you think about.
Source: How to Win Friends and Influence People

Failing Forward: How to Make the Most of Your Mistakes

Source: The Success Journey: The Process of Living Your Dreams

Sententiæ: The Citizen and the State, p. 624
1940s–present, A Mencken Chrestomathy (1949)
Source: A Mencken Chrestomathy

Zig Ziglar
200 Motivational and inspirational Quotes That Will Inspire Your Success
Variant: Your attitude determines your altitude. - Zig Ziglar

Source: A Heart So Wild

Variant: The secret of genius is to carry the spirit of the child into old age, which means never losing your enthusiasm.

Source: Extremely Loud and Incredibly Close

Source: Sayings of Confucius