When I run into disappointment - say, for example, not getting a role I'd hoped for - I just try not to take it personally.
I didn't grow up imagining myself as an opera composer. Only once in my entire adolescence did I attend an opera. I went and saw Aida at the old Met, didn't understand a thing about it, and thought it was pretty awful. But I think I had it in my genes without even realising it.