Although this quote has been attributed to Wittgenstein in Wittgenstein's Mistress by David Markson, there is no verifiable source from Wittgenstein that it can be traced back to.
Disputed

“I work quite diligently and wish that I were better and smarter. And these both are one and the same.”

Ludwig Wittgenstein

In a letter to Paul Engelmann (1917) as quoted in The Idea of Justice (2010) by Amartya Sen, p. 31
1910s

“Frazer's account of the magical and religious views of mankind is unsatisfactory; it makes these views look like errors.”

Ludwig Wittgenstein

Source: 1930s-1951, Philosophical Occasions 1912-1951 (1993), Ch. 7 : Remarks on Frazer's Golden Bough, p. 119

“I believe it might interest a philosopher, one who can think himself, to read my notes. For even if I have hit the mark only rarely, he would recognize what targets I had been ceaselessly aiming at.”

Ludwig Wittgenstein book On Certainty

387.
On Certainty (1969)

“It seems to me that, in every culture, I come across a chapter headed Wisdom. And then I know exactly what is going to follow: Vanity of vanities, all is vanity.”

Ludwig Wittgenstein

Conversation of 1934
Personal Recollections (1981)

“It is one of the chief skills of the philosopher not to occupy himself with questions which do not concern him.”

Ludwig Wittgenstein

Journal entry (1 May 1915)
1910s, Notebooks 1914-1916

“One might say: Genius is talent exercised with courage.”

Ludwig Wittgenstein

Man könnte sagen: „Genie ist Mut im Talent.”
Source: Culture and Value (1980), p. 38e

“You could attach prices to thoughts. Some cost a lot, some a little. And how does one pay for thoughts? The answer, I think, is: with courage.”

Ludwig Wittgenstein

Variant: You could attach prices to ideas. Some cost a lot some little. … And how do you pay for ideas? I believe: with courage.
Source: Culture and Value (1980), p. 52e

“Kierkegaard was by far the most profound thinker of the last century. Kierkegaard was a saint.”

Ludwig Wittgenstein

As quoted in "Wittgenstein and Kierkegaard on the ethico-religious" by Roe Fremstedal in Ideas in History Vol. 1 (2006) http://www.ideasinhistory.org/cms/index.php?page=wittgenstein-and-kierkegaard-on-the-ethico-religious <br class="br">Attributed from posthumous publications

“What I give is the morphology of the use of an expression. I show that it has kinds of uses of which you had not dreamed. In philosophy one feels forced to look at a concept in a certain way. What I do is suggest, or even invent, other ways of looking at it. I suggest possibilities of which you had not previously thought. You thought that there was one possibility, or only two at most. But I made you think of others. Furthermore, I made you see that it was absurd to expect the concept to conform to those narrow possibilities. Thus your mental cramp is relieved, and you are free to look around the field of use of the expression and to describe the different kinds of uses of it.”

Ludwig Wittgenstein

Lectures of 1946 - 1947, as quoted in Ludwig Wittgenstein : A Memoir (1966) by Norman Malcolm, p. 43
1930s-1951

“For a large class of cases — though not for all — in which we employ the word meaning it can be explained thus: the meaning of a word is its use in the language.”

Ludwig Wittgenstein book Philosophical Investigations

§ 43, this has often been quoted as simply: The meaning of a word is its use in the language.
Philosophical Investigations (1953)

“My aim is: to teach you to pass from a piece of disguised nonsense to something that is patent nonsense.”

Ludwig Wittgenstein book Philosophical Investigations

§ 464
Philosophical Investigations (1953)

“It's impossible for me to say one word about all that music has meant to me in my life. How, then, can I hope to be understood?”

Ludwig Wittgenstein

“Language is a part of our organism and no less complicated than it.”