Three things have been frustrating me lately (and historically, and probably always will):
1) Technology (crashes, malfunctions, etc) - My lovely darling computer has been acting up a storm lately. I'm trying to deal with it, but I also still need to use it for work.
2) Lack of motivation - I try to compensate with discipline, but forcing myself tends to exacerbate my anxiety and has caused me months upon months of creative block before. Lengthy periods of creative block are the absolute worst and are usually coupled with lengthy periods of terrible depression. :U
3) Other projects and obligations - I have a lot of hobbies and things I want to learn and things I need to be doing. There is just not enough time. Right now my motivation for game dev has been making my comic suffer a bit. I wonder if I'll ever get the balance right?