“I'm 40 now. When I'm dead, hopefully this house will still be going.”

Source: It's Kind of a Funny Story

On Writing Poetry (1995)
Context: I no longer feel I'll be dead by thirty; now it's sixty. I suppose these deadlines we set for ourselves are really a way of saying we appreciate time, and want to use all of it. I'm still writing, I'm still writing poetry, I still can't explain why, and I'm still running out of time. Wordsworth was sort of right when he said, "Poets in their youth begin in gladness/ But thereof comes in the end despondency and madness." Except that sometimes poets skip the gladness and go straight to the despondency. Why is that? Part of it is the conditions under which poets work — giving all, receiving little in return from an age that by and large ignores them — and part of it is cultural expectation — "The lunatic, the lover and the poet," says Shakespeare, and notice which comes first. My own theory is that poetry is composed with the melancholy side of the brain, and that if you do nothing but, you may find yourself going slowly down a long dark tunnel with no exit. I have avoided this by being ambidextrous: I write novels too. But when I find myself writing poetry again, it always has the surprise of that first unexpected and anonymous gift.

Personal motto, on the title page.
Variants: Be sure that you are right, and then go ahead.
As quoted in David Crockett: His Life and Adventures (1874) by John Stevens Cabot Abbott, who indicates that he also often used simply "Go ahead!" as a battle cry, and general assertion of determination.
Unsourced variants: Be always sure you are right — then go ahead.
Be sure you are right — then go ahead.
Always be sure you are right — then go ahead.
A Narrative of the Life of David Crockett (1834)

"Bad Meets Evil" (Track 19).
1990s, The Slim Shady LP (1999)

"'It never gets any easier'" in The Guardian (23 February 2004) https://www.theguardian.com/film/2004/feb/23/1

tick, tick... BOOM! (1990)

"Bad Meets Evil"
1990s, The Slim Shady LP (1999)

Source: Dead and Alive

"I'll Sleep When I'm Dead"
Warren Zevon (1976)