I need some ENERGY!!!!! Help!!

OK, I work at at school. I am in the computer lab. I see 700 plus 3/4 graders in 3 days!! I'm trying to get back in my workout routine. After being off all summer, its hard to get going!! And by the end of the day my GET UP AND GO has GOT UP AND GONE!!! And morning work outs are not an option!!

Tuesday and Thursdays and Saturday are gym class days (PACE on Tuesday/PUMP on Thursday/Boot camp on Saturday). I need a little 'boost" on those days. Ive tried SPARK, Crystal light energy, even SF Monster!!! Any other ideas?????????