it's pretty easy if you're not wasting a lot of time, try and make sure you do things in a time efficient way e.g. go to the gym on the way to/from uni to save an extra trip, don't spend 30 mins showering before class then 30 mins showering after the gym later as well, if you can fit in a gym session between classes that's a good option
personally I always prefer to get up early and work out before whatever I have to do that day because then it's done and it's only time you would have been asleep anyway