I don't like the word "frustrating." Something that is frustrating to me is something that is out of your control, like waiting in line at the DMV. I prefer the word "challenging" - they may be difficult, or even nigh-impossible, but they can be overcome, and you will probably learn something in the process. Challenges inspire. If you think of all your programming problems as challenging rather than frustrating, you are a happier person. :)