Making a commitment is never easy, and it's even more difficult to stick to it. However, to derive maximum benefits out of you exercise regime, you need to continue it on a long-term basis. Here are a few things I have found very effective at helping me to keep at it.
1. Set small, achievable goals so you are able to track your progress. Achieving these goals will also keep you motivated.
2. If you want, you can also put it down on paper and keep it where it's visible, for example -- on the refrigerator door. If you see what you anted to achieve, it will be all that more difficult for you to miss the exercise.
3. This has been a lifesaver for me. Get a buddy to exercise with. Knowing that a friend is waiting for you to begin their walk will not allow you to skip it. You could even join something new so that it doesn't get boring.
4. Finally, if you managed to achieve something, no matter how small -- feel good about it and gift yourself something nice to celebrate.