You raise an interesting point, and I agree that motivation is largely about what's important to me. This is likely an overgeneralization on my part, but I see life as full of things that I will have to do which don't really have a point. At least all the way through college it's been that way, always the hope that there's less bullshit at the next level and always the disappointment.
If you think about it long enough, it inevitably turns out that nothing really matters.
The bad part is that it's technically correct[0]. The good part is that once you know it, you have the advantage. Things stop being divided into things that have a point and those that don't. Hence your life stops being full of unimportant things, as ultimately they're all equally significant (or insignificant).
After that, my thinking usually goes the following order: 1) Why do anything at all in such circumstances, life has no point, etc. 2) Wait, I still might as well enjoy the process.
For some reason, the latter normally looks superior (if I'm in good shape), so I'm trying to learn to enjoy the process. Turns out it's not as simple as doing what is pleasant. For me, it's pleasant to drink beer and eat junk food, but it hurts the enjoyment part in the long run. The trick is more about ‘loving what you do’. I'm not really there yet.
I'm a dropout. I guess if I had come to above reasoning back then, I would probably finish.