Yesterday is history, Tomorrow is a mystery, Today is a gift.
I saw this quotation in 2004 written above the entrance to the nuclear physics centre in South Korea. The exact origins of the phrase seem to be unknown although several possibilities exist.

You should keep in mind that there are only twenty hour in a day. Four hours must be set-aside for meditation. Fu Szu-nien, president of the National Taiwan University (January, 1949-December, 1950). I was told this story during my visit to Taiwan. Quoted from my memory

Sometimes it’s a little better to travel than to arrive, Robert M. Pirsig

To live for some future goal is shallow. It’s the sides of the mountain that sustain life, not the top. Robert M. Pirsig

The only Zen you can find on the tops of mountains is the Zen you bring up there. Robert M. Pirsig

When you come to a fork in the road, take it. Yogi Berr (on quantum mechanics?)

Physics should be made as simple as possible, but not simpler. Albert Einstein (attributed, after hearing a philosopher lecturing on relativity)

Three laws of discovery (collected by Professor Sir Michal Berry)
Arnold’s law (implied by statements in his many letters disputing priority, usually in response to what he sees as neglect of Russian mathematicians)
Discoveries are rarely attributed to the correct person
(Of course Arnold’s law is self-referential.)
Berry’s law (prompted by the observation that the sequence of antecedents under law 1 seems endless)
Nothing is ever discovered for the first time
Whitehead’s law (quoted by Max Dresden at the beginning of his biography of Kramers)
Everything of importance has been said before by someone who did not discover it.

Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart. Steve Jobs

Again, you can’t connect the dots looking forward; you can only connect them looking backwards. So you have to trust that the dots will somehow connect in your future. You have to trust in something — your gut, destiny, life, karma, whatever. This approach has never let me down, and it has made all the difference in my life. Steve Jobs