With revision going into full swing, most students reading this probably don't have that much free time at the moment. So here I have a few ways of quickly getting a work out in without having to sacrifice too much revision time. Also, you don't really want to workout too hard when you're revising as you want your body to have plenty of energy so your brain power will be at it's fullest.
The first way of getting in a quick bit of exercise without revising is to go for a brisk 10-20 minute walk before eating breakfast. Don't go at a high intensity as you will start to break down muscle instead of fat.
Secondly is doing quick exercises at home instead of the gym. Try visiting www.youtube.com/sixpackshortcuts for some quick and effective workouts that I often use myself.
Try to rest less between sets, this means that you can't do as many reps but it means you'll get tired much quicker and it won't take as much time to workout.
A quick way of doing this is drop sets. This is where you do 12 reps of an exercise at a pretty heavy weight for you and rest for 8 seconds, then do 8 reps and rest 8 secs, then 6 reps and then 4 reps. This counts as 1 set. you should rest between 1 and 2 minutes and then go for another set. You should do between 2 and 4 sets, of 3 different exercises. This shouldn't take you much more than 20 minutes and you will definitely be feeling it afterwards. A second way is doing supersets, this is where you do a set of one exercise and then go straight into a second set of a related exercise without rest (eg dips and then straight into tricep extensions or squats and then into a wall sit). By cutting down on the amount of rest and doing extra sets without rest you will be able to do quicker, more intense workouts that will leave just as pumped, or even more pumped than a normal workout.
By doing short, intense workouts and eating right you should be able to keep revising whilst also maintaining your body, but this method of working out can also be a legitimate strategy all by itself. Just remember to eat enough so that your body has plenty of nutrients and your brain function and revision time won't suffer by keeping fit.
Good luck :)