Pre-workout energy boost

Hey everyone! I'm looking for some advice. I work at a gym (pretty convenient) and I also go to school full-time. Between work and school I rarely have time to actually workout and when I do, I'm so exhausted from studying and going back and forth between school and work. I was wondering what people do to give them an energy boost. I used to work out in the evenings, but I found I wasn't very successful doing that. I would like to start setting time aside in the morning, but it seems like my body doesn't want to do anything in the mornings. I need help! I was thinking about maybe starting a pre-workout supplement to get me going again. I'm pretty small (5'2, 125 lbs) so I wouldn't take a very large dose. Has anyone used pre-workout supplements? what did you think? Any other suggestions?!