The time away from the family is the hardest part of the job. I have a little apartment in D.C., and I have to tell you, I'm happy when I get to go home to Georgia. My wife and I are also talking about whether we can afford the apartment or not. If not, I guess I'd sleep in my office like a lot of my colleagues do.
The hardest part about improv is getting the audience to relax and enjoy themselves, because most improv is not very good, and the audience is nervous for the performers the whole time. Not that they don't even like the show, but they feel bad for the performers.
There were times when I was working three jobs at one time, and I was still auditioning just to make ends meet, and I was hoping that something was going to come through. Especially after you have two degrees, standing solid through the process is sometimes the hardest part because there is no guarantee.
The hardest part about acting is realizing it doesn't matter.
The hardest part about writing fiction is finding long stretches of time to do it: for me, this means writing mostly on Saturdays and Sundays. But I am always thinking about my characters, jotting down ideas in stolen moments and hoping I'll be able to make sense of them when the weekend rolls around.