First up, a couple pieces of wisdom from Bob Ross:
(For lots more Bob Ross wisdom, about art - and life, check out this link that I found: Zen of Bob Ross on Tumblr)
Those last two are ones that I really need to try to remember.
Setbacks are very hard on me, even crippling. Also, I spend a lot of time thinking I'm bad at everything (including riding and most artistic things). However, I'm certainly not satisfied being "bad at everything", I'm constantly trying to learn more, so I suppose there's hope!