School help please and thanks?

I am really doing a lot better in school this semester but I'm afraid that I'm going to start slacking off and I really want to keep my grades up for when collage approaches. I'm off to a good start with habits that could give me a 3.5 gpa. However I don't want to slack off either because I plan on taking the vocational tech nursing program then come out as a lpn go to collage become an rn. Then go into either the military or army (either one I go into I do not want to go on the field). Any tips to keep me from slacking off?