Hmmm.......

"You've got to jump off cliffs all the time and build your wings on the way down."
Annie Dillard

First you jump off the cliff and you build wings on the way down.
Ray Bradbury

“Sometimes you just have to take a leap and build your wings on the way down”-Kobi Yamada
(btw, Yamada is in his 30's and owns an inspirational card company, so I'm sure he wrote it! )