I can TOTALLY understand you. Drawing has always been a huge hobby of mine, but I have pretty much stopped doing it because I was never satisfied with what I drew and eventually just gave up. :( I can still appreciate gorgeous art though, I just always think, "Wow, that's beautiful... I'll never be able to do something like that!". Now it's not so bad anymore, I still draw occasionally, I've just... sort of accepted I'm not really good at it, haha.

I think most artists go through a similar phase. I think the best thing you can do is just to keep sticking with it, even though it's frustrating. Eventually it will get to a point where it's not frustrating anymore! :)

(This is probably not very good advice... mainly because this happens to me as well sometimes and I don't know myself how to deal with it...)