Help me with this please! Be detailed.?

Okk. I always at the begiining of school i say "I will make good grades this year, then about 4 or 5 wks into the school year, i seem to start to not care! I try to get back on track, and it just doesnt work! Any ideas on how to fix this problem? I try then just seem like i cant ever get back on the right track again!