Long-term motivation: High energy is my motivation. I suffer from low energy, so if I don't pay strict attention to sleep/food/workout, then I have low energy all day long and life is generally no fun. The way I keep it up is by having a crystal-clear plan (sleep plan, meal plan, workout plan). I've found that if I don't have a plan, it's easy to drift and make excuses, but if I do have a plan, then I know exactly what I'm supposed to do that day as far as bedtime, food, and exercising.
Short-term motivation: Exercising isn't too much fun for me, so I have to trick myself into exercising and entice myself to keep on doing it. As part of my workout plan, I have a specific time and length that I do it every day (5:30AM, for 30 minutes). I have an alarm that reminds me when I do it. Then I put on my exercise clothes (jogging pants and a bright red breathable shirt), this makes me "feel" like I'm ready for exercising. Then I either go biking with a buddy, or I use Netflix - I have a small TV in front of my exercise equipment to keep me entertained for cardio. That way I have something new & interesting to look forward to every day. I've learned that if I'm not specific with myself, it's really easy to make excuses.
So for me, my main goal is to have high energy. To make that happen, I have a plan and then "trick" myself into doing it every day and make it interesting by watching movies or working out with a buddy. That seems to work pretty well for me.