It depends.

If you mean the state of being/consciousness called Flow, as it was enunciated by Mihaly Czhicksentmihyi(spelling?) in his book with that title, then I have to say it was when I was on stage presenting my found songs, and everything was clicking better than ever. As M.C. said, and I paraphrase: "Time truncates and/or diminishes. It's passing becomes nearly un-noticeable--almost an easy and accessable proof of Einstein's relativity stuff. Everything seems heightened--almost glowing. You can do no wrong in that zone.---And, then, next, you find, fantastically and amazingly, that you have an encore or two to do."

That sounds to me sort of like what cocaine must be like for some.

On another tack: I never felt so alive as I did many times when I was singing five months a year, every other day, for ten solid years, on Mississippi River steamboats. It wasn't so much when I was playing, then, as it was when I was free to luxuriate in the serenity, the colors, of the river---no matter whether it was during a storm, or just a lovely and tranquil day out there. It could be sublime!

On the back of John Hartford's fiddle, a photo of which is in my "forty years of folk scene photos" website, he had an inscription inlaid around the bottom of   the instrument's back saying: Nothing Is Real But The River, And All Else Is Sham.

----- I understood how he felt!

Art Thieme