I have always walked a lot (an average of 10 daily kilometers) for the last 20 years or so (I´m 37). That kept my weight in relatively healthy levels despite gaming, eating and drinking more than I should had. That said, two months ago I started running almost every day (between 6 and 15 daily kilometers) and the effects on my body have been surprising. Combining it with boxing and biking, I have been able to lose 12 kilos in that time span (I started at 95, currently at 83, final objective is to stabilize around 78). My stamina and self-esteem have both vastly improved.
I even downloaded some apps (Adidas Runtastic, etc.) to keep a better check on my running routine. Next objective: buying quality, specialized running shoes.