1. Do a variety of activities you enjoy. There is no rule which says you have to go to the gym or buy expensive gym equipment. Having a variety of activities such as yoga, soccer, tennis, cycling, and aerobics classes will help ensure that you will always have something to do regardless of the weather or time of day.
2. Commit to another person. It is easy to let yourself off; agreeing to work out with a friend makes it harder to let yourself off at the risk of letting them down.
3. Make exercise a priority. It has to be a non-negotiable.
4. Exercise first thing in the morning. Experts agree that a morning schedule is best.
5. Or, exercise on your way home from work/class. The next best thing to exercising first thing in the morning is to do it on your way home from work/class. Don't go home first, there aren't a lot of people who are so motivated that after they go home and change clothes will go back out again and exercise."
6. Exercise even when you're "too tired." Chances are you'll feel better after exercising.
7. Log your activity. Write down the things that are important to you. It could be how much time you exercise each day, how many steps you walked, how far you ran or cycled, what you weighed, etc. Some people make a game of it. You may have heard of runners calculating the miles it would take to run from their homes to Boston (home of the famous marathon), figuring how far they run in an average week and setting a target date for "arriving" in Boston.
8. Be aware of all the indicators of progress. It's great when your clothes fit better and you can lift heavier weights or work out longer without getting exhausted.
9. Walk -- with a pedometer. "If you enjoy walking and haven't exercised for awhile, 10 minutes three times a day will give you 30 minutes. Use a pedometer, and work up to at least 10,000 steps a day. Nobody starts out with 10,000 steps. Find out what your daily average is, and, strive to increase the number of steps each week.
10. Reward yourself. Experts say that making behavior changes is hard, and rewards motivate. So decide on a goal and a reward, and work toward it. Rewards can be anything from a new pair of shoes to a night out with friends, do whatever works for you.
Adapted from:http://www.webmd.com/fitness-exercise/guide/exercise-habits?page=1