... but doubt is what gets you an education.
I've always been a learner. I continuously in school from 1970 (well, before that if you count high school) until 2001. Then I took Community Ed classes in French, pottery, and everything imaginable.
It's only been since 2004 that I haven't been in school. You know why? Yep. I'm writing. I found something else to satisfy that creative need of mine.
I toyed with the idea of getting a PhD but then thought, heck, why bother? I have a B.A., M.A., B.S., M.S., and A.A.D. Do I need anything else? I'd much rather do what I love to do, and that's write down the stories that are swirling in my head. So I learned how to write and I continue to learn how to write, with every book I write.
Never stop learning. It will keep you young.