Why do I always let this happen?

So it has happened again. I have gotten myself way too involved! Part of me thrives off of this non-stop lifestyle, but the other part of me knows it is not good for me. I have over committed myself again and am not resting nearly as much as I should. I definitely want to be doing all of the things that I am, but it is hard to stay caught up on sleep and school work when you involved in too much. Sometimes it really sucks being interested in so many things! By the time I get home at night my body is so tired from going all day that I do not even want to do school work. My mind is generally okay at this point, but of course the fatigue my body is feeling begins to take a tole on my mind. As soon as I allow this to happen to my mind, I can no longer live presently. So the longer I let all of this go on, the more all of the things I am doing become things that I am just doing because I have to not because I want to anymore. At this point I am loosing the desire that I once had to do these things because I am so tired. WHY does this always happen? I thought I had learned, but apparently not. I have got to stop doing and take time rest. I am working on fixing this. I am working on figuring out how to decided what is really important for me to be doing and what is not. Sometimes being an adult sucks. I really would just love to go back to being a kid and being fairly carefree.