I saw that on Pinterest, and I really like it. It's a good philosophy that I think applies to virtually everything. I have made lots of mistakes and I really appreciate the sentiment that I'd have never made them if I wasn't at least trying. Trying is better than not trying.
If I still had a classroom, I'd post a big poster: Mistakes Are Proof That You Are Trying. I'd print it on sticky notes and attach them to tests.
(Actually, now that I said that, I think I may do that last part anyway.)
(Heck, I may just make five copies of the same poster and hang it in every room I visit.)
Anyway, I like it and wanted to share it. Hopefully you find some inspiration in it as well!