I think the biggest thing affecting my schoolwork (I'm in college, on the GI Bill-- don't know if I ever really said so before) lately is that I'm a lonely student. It's hard to have a school-centric social life that includes study time when none of your friends and associates have to worry about school and doing homework.
It's also lonely to be the only person you know with PTSD-- I'm sure I know people who have to deal with it. It's not something that comes up in normal conversation. I don't normally like to share my problems with others in person because hear other people complain constantly about their individual problems. And they sound like whiny little bitches, which is something I am most certainly not.
Anyway, I think environment has a lot to do with my happiness, and my sense of calm. If I'm in a safe, academic centered environment such as on campus, or in a coffeehouse where everyone is studying something, then I'm much more likely to study myself. On the other hand, if I'm at home, there's no one else here to be studious. It's too easy to be distracted because home is not an environment that's geared towards doing homework.
In fact, other than the times when I'm in class (and the time before class, when it's convenient to be at or near campus studying), I don't have much at all around me that supports being a student. If anyone at work is in school, they don't talk about it, and most people there are happy working for a company that sucks because they get free health insurance. I'm a member of one of the bigger veterans' groups, and no one there is in college. The other students I know from my second job, or in class, have schedules that are so different from mine that there's no hope of a regular schedule for study sessions. So that leaves me alone, and frustrated, and feeling hopeless a lot. The voices in my head, damn them, are always going to tell me I'm a failure when I'm alone.