1. First and foremost, realize if you don't do something, you're body will atrophate. Your activity level will drop even more, and you'll eventually lose the ability to move. That should be motivation enough.
2. Do you want feel like the fit guy or the fat guy? Self image is really important, taking positive steps to change the way we look and feel, especially when you get results, keeps you at it.
3. Don't overdo it to soon. The typical mistake of most impatient Americans who expects results yesterday. Sorry boys and girls, that's not the way it works. Results come tomorrow, start SLOW.
4. Really know what you want from exercise. You should have a destination and a road map, or else you're gonna get lost.
5. Be consistent, but don't worry about being perfect. Bounce back from missed workouts, or bad weekends, fast, don't lose your mojo.
6. Lastly, take pride in every little step. As long as you're headed in the right direction, the sky's the limit.