The beginning is constantly available, but you must start…

“In order to love your enemies, you must begin by analyzing self.”

Martin Luther King, Jr. (1929–1968) American clergyman, activist, and leader in the American Civil Rights Movement

1950s, Loving Your Enemies (November 1957)
Context: How do you go about loving your enemies? I think the first thing is this: In order to love your enemies, you must begin by analyzing self. And I’m sure that seems strange to you, that I start out telling you this morning that you love your enemies by beginning with a look at self. It seems to me that that is the first and foremost way to come to an adequate discovery to the how of this situation. … some people aren’t going to like you. They’re going to dislike you, not because of something that you’ve done to them, but because of various jealous reactions and other reactions that are so prevalent in human nature. But after looking at these things and admitting these things, we must face the fact that an individual might dislike us because of something that we’ve done deep down in the past, some personality attribute that we possess, something that we’ve done deep down in the past and we’ve forgotten about it; but it was that something that aroused the hate response within the individual. That is why I say, begin with yourself. There might be something within you that arouses the tragic hate response in the other individual.

“The beginning of it starts at the end”

Tom Waits (1949) American singer-songwriter and actor

“Because you see it starts now, it didn't begin in the past, there was no past.”

Alan Watts (1915–1973) British philosopher, writer and speaker

On deep meditation and enlightenment that transcends temporal experiences and most notions of selfhoody
Alan Watts Teaches Meditation (1992)
Context: [Successful meditation brings about realizations:] That we are no longer this poor little stranger and afraid in a world it never made. But that you are this universe and you are creating it in every moment... Because you see it starts now, it didn't begin in the past, there was no past. See, if the universe began in the past when that happened it was now; see, but it's still now — and the universe is still beginning now, and it's trailing off like the wake of a ship from now, and that wake fades out so does the past. You can look back there to explain things, but the explanation disappears. You'll never find it there.... Things are not explained by the past, they are explained by what Happens Now. That Creates the past, and it begins here... That's the birth of responsibility.

“And suddenly you know: It's time to start something new and trust the magic of beginnings”

Meister Eckhart (1260–1328) German theologian

Widely circulated on the internet, but no actual text to tie it back to Eckhart, as of yet.
Ref: en.wikiquote.org - Meister Eckhart / Disputed

“Architecture starts when you carefully put two bricks together. There it begins.”

Ludwig Mies van der Rohe (1886–1969) German architect

“Starting today, we must pick ourselves up, dust ourselves off, and begin again the work of remaking America.”

Barack Obama (1961) 44th President of the United States of America

2009, First Inaugural Address (January 2009)
Context: We remain the most prosperous, powerful nation on Earth. Our minds are no less inventive, our goods and services no less needed than they were last week or last month or last year. Our capacity remains undiminished. But our time of standing pat, of protecting narrow interests and putting off unpleasant decisions — that time has surely passed. Starting today, we must pick ourselves up, dust ourselves off, and begin again the work of remaking America.