Hey bud,

It's hard to tell, everyone gets motivated by different things... Anyway, what works for me goes along the following;

1. Having clear, attainable goals;
2. Tracking your workouts/measurements so you can have a clear picture of your progress;
3. Finding a workout buddy who has similar goals;
4. Getting involved with varying activities, i.e. jog for week, cycle for another, try swimming - variety is key for your success;
5. Going outside - if weather permits, go to the park instead of the gym - you'll see new people, enjoy fresh air, and maybe get a suntan!
6. Get some really good music into your iPod - it makes wonders, especially when you're doing some cardio... Motivating songs help you reach that extra mile!
7. Find the best time for you to exercise - at morning, I can't lift a feather, my peak performance is reached around mid-day.
8. Stay groomed - it really pays off when you're bending necks @ the gym!

Well, that's it, hope it helps!

Peace, Roland