Why not give it a go, all you have to do is just step outside your door and get moving!
Not only will you save money on a gym membership. You'll be getting your vitamin D and breathing in fresh air instead of being exposed to the artifical lights and recycyled air conditiong of the gym. If that doesn't motivate you to exercise outside, then maybe the fact that you are much more likely to burn excess calories exercising outside then you are in the comfort of your gym. Why?
Well firstly you are being exposed to different temperatures & terrains which will make your workout much harder, but also because you are more likely to enjoy your workout when you are outdoors, which results in more time spent exercising.
If time is an issue (let's face it, when isn't time an issue for a uni student!), you dont need to get to a gym or sports centre in order to get a little exercise into your daily routine. If you live close enough, walk to your lectures instead of catching the bus, or even catch the bus to a distance were you could still walk some of the way. Ride your bike to and from class (If you have one of course) .If your going out during the night, get up and dance with your friends, so much fun and your keeping active at the same time. Use your break inbetween lectures and tutorials to go for a walk, run or ride around campus.