I went to college somewhere with a HUGE campus. For the first time in my life, I was suddenly walking miles and miles a day. Probably 5-10 miles a day. I also ate less because the cafeteria food grossed me out. Unlike every college freshman ever, I lost 30 pounds in a year. (I've pretty much kept it off ever since--20 years!) I eventually switched to running because I don't have as much time anymore. But as soon as I have fewer demands on my time, I will go back to walking a ton.