I agree with Almeeker, i have lost 13lb in the past 2 months JUST by riding to college. I ride 6 days a week and its about 15/20minutes each way. I have so much more energy now than i did before i started.... and i could have bought a car and started to drive but i am also like you and needed the exercise to 'flow' with my schedule. Taking an hour to go to a gym doesn't stick with me.... i need it to not interfere with my day!
So... cycling has worked for me so far