mind over matter

The basis of your heart rate is your anaerobic threshold (AT). For most people this represents, in heartbeats per minute, the point at which your body shifts from using fat as fuel to using sugar. To determine your AT, first subtract your age from 180. This is the starting point. During your next workout, push just to the point at which you run out of breath. Record that number on your heart rate monitor. This ventilatory threshold usually coincides with your anaerobic threshold, so take the average of these two numbers. That is your true AT, the point at which you maximize your fat burning potential and where you should spend the vast majority of your exercise time.

6 Bite-Size Workouts

If you view long, difficult tasks as a string of single steps, you will perform far better and with greater ease. Think in terms of small chunks of distance or time: five-minute segments or half-mile increments rather than the whole time or distance. You'll find that this approach keeps you focused on the present and on doing your best each step of the way.

7 No Guilt--Seriously

Guilt is a useless emotion. Think about it: You decide to do something, and afterward you realize it wasn't a good decision, so you get mired in guilt. Meanwhile, nothing gets done.

We've all felt guilty about missing a workout. I say either do the workout and feel great about it, or skip it and feel equally great. Make the most of that free time and simply commit to getting right back to business the next day. The worst part about guilt is that it keeps us from enjoying the fact that we just skipped a workout. Remember: You can get back on track at any moment, whether it's after one day or one year.

8 Go Longer, Less Frequently

The traditional advice for aerobic exercise is 20 minutes, 3 times a week. Unfortunately, that doesn't nearly cut it. To reap the real aerobic (or fat-burning) effects of exercise, you've got to workout for at least 45 minutes at a time. It is much more beneficial to do three 45-minute sessions per week than five 20-minute workouts because your aerobic system takes a while to get rolling along. Only after 20 minutes of continuous aerobic exercise does your body begin to reap the benefits. It is only then that you begin burning body fat.

9 Run Like the Wind

For cardiovascular fitness and fat burning, running is king. It is a high-intensity, weight-bearing activity. The only problem is that it carries a high risk of injury. Here's how to prevent that from happening.

* Never run more than five days a week.

* Hit the weight room and develop balanced strength by isolating your muscles with single-arm and single-leg exercises (have a trainer help you get started). Many running injuries come not from muscular weakness, but from muscular imbalance.

* Always stretch after a workout, while your muscles are warm.

* Buy the right sneakers. The experts at most sporting good stores can help you determine which shoes best suit your biomechanics. There are countless types of running shoes and today's technology can improve your running experience.