How Do They Do It?

Now that my Croatian class at Berkeley is over, I am left to beg the question: How do people do work and school at the same time? More to the point, how do some do full time work and full time school at the same time?
I cut back to a mere 20 hours per week so I could take this class that was every day and required a two hour round trip to get to. This had the net effect of making me pretty damned tired all the time. And fuzzy. And just generally kinda out of it. I know that when the work load increased, my grade decreased and vice versa.
I gotta say that I have nothing but respect for people who are able to pull this off successfully. I guess it’s the drive of bettering oneself, one’s career, and one’s life that keeps them going. That and maybe that there is a light at the end of tunnel in two or four years. I don’t get it, but I’m glad I didn’t have to the full on craziness. I’ll have to see if I take this class next semester. It’s going to be a lot of work again, but it might be worth it of course.