The most practical is of course running. If your serious then GET SERIOUS. Get good running shoes and invest in some type of mp3 player. Put songs on it that will keep you going, I listen to trance which helps me run further. The treadmill is great because you can see and control how much you do. Watch how things progress on the treadmill and you will be amazed. Make sure to drink pleanty of water during the day and try not to drink too much right before the run.