BETough

In my program, students take classes for the first two years along with starting research and then focus on research after that. I'm finishing up my third semester, so I'm nearly done with classes, but this past semester has just been brutal. I'm passing my classes (I could be doing better, but I know classes aren't very important and I'm in no danger of failing), and I think my advisor is reasonably happy with my progress in research, but I have been pretty much constantly stressed since my quals last summer, and the idea of putting myself through another 4-5 more years of this seems so daunting right now that I'm doubting if I can do it. I think my research is interesting, and I do enjoy it when I have opportunities to recharge my batteries, but lately I've been constantly either doing lab work or working on projects for class. I'm so burned out that even doing things that I previously found interesting is a chore. I try to force myself to take breaks and do things I enjoy, but even then I often find myself stressing out about how I'm wasting time that I could spend doing work. I know that a lot of, if not most, people think about quitting at some point in their Ph.D., but is what I'm feeling normal? Does anyone have any suggestions for how to deal with it? Do things get better when you can just focus on research?