Sometimes it seems like I spend my whole time trying to keep myself awake and I don't really meditate.
Lethargy and sleep come during meditation because sincere interest is lacking. If sincere interest is there, there will be no tendency to sleep. When a student wants to be first in school, when he has a real, sincere interest, then he studies without being forced by his parents. But some students feel that if they just pass the examination, that is more than enough. If this is their reeling, then they do not have any energetic drive or enthusiasm for their school work.
You should always try to be eager and enthusiastic about meditation. If you feel that you cannot meditate for half an hour, then plan to meditate for ten minutes. Then you will feel, "Oh, only ten minutes. Easily I can do that." If your goal is very near, then you will give it all your energy. If it is quite far, you will say, "Oh God! To keep running at top speed for such a long time is impossible." But anybody can meditate for ten minutes. If you have to run twenty miles, you will be scared to we death. But if you see that the goal is within sight, then you will say, "Oh, I can easily reach it. Let me run as fast as possible."