What happened to turning off the tube and going for a walk???
Not watching your diet, you could make the same mistake I used to make and go run hardcore, then stuff yourself when you get home. The result....you're still fat, except you can run good.
What a great idea! Bring along a good portable music player (I'm using a skip-protected CD player nowadays) and listen to music while doing long, long walks. I usually walk about 40-50 minutes a day for good exercise.