My biggest vice is leaving for lunch everyday during work and driving thru a fast food joint. I'd gone about a week until yesterday, my body wasn't liking going without the chemicals.
Sounds stupid, but I have a Jillian Micheals dvd called 30 Day Shred. It's interval training, mix of cardio and weights, you just need some 3lb dumbells to start, doesn't seem like much but trust me, unless you lift the 3 lbs will cause pain.
You can find the videos on youtube, the girls are hot so that helps and it's things like jumping jacks, push ups, squats, some ab stuff. It really does work if you can stick with it. It's only about 25 minutes including the stretching so it's quick. Has 3 levels, you're supposed to do each level for 10 straight days. It's tough, when I get started I usually do every other day until my body can handle it and I don't feel like my heart is going to explode.
Push yourself but take it easy, injuries won't do you anygood.