The spark of inspiration behind The Spark came when Glenn Gaesser looked at the exercise recommendations he and his fellow exercise scientists at the American College of Sports Medicine had come up 20 to 60 minutes of vigorous aerobic exercise, three to five times a week; two to three strength-training sessions a week; and two to three flexibility workouts a week. That's the recommendation for the "average" person. No wonder the population keeps getting fatter, Gaesser thought. Other than athletes, models, fitness professionals, and a handful of gym rats, who had time for all that? The people without the time--the vast majority of the unexercised population--couldn't see the point of doing anything less. Armed with some intriguing research showing that three 10-minute aerobic exercise sessions in a day produced equivalent benefits to one 30-minute workout, Gaesser tried something a workout program consisting of 15 10-minute bursts, or sparks, of exercise. He tried this on a sedentary group of women and found that in three weeks they lost weight; lowered their cholesterol and triglycerides; and improved their aerobic fitness, flexibility, strength, and muscular endurance. In other words, in just three weeks, these women achieved results normally seen in three months of an exercise program. Why do these 10-minute sparks work so much faster than traditional exercise programs? Partly because of growth hormone, an important muscle-building and fat-mobilizing chemical your body releases during and after exercise. If you get three daily surges of growth hormone, you get triple the benefits of one daily surge. Besides showing how to get off the couch and start sparking, Gaesser includes nutritional recommendations. He's a rarity a high-carbohydrate advocate. (He cites a University of Pittsburgh study showing that people of all ages who've lost weight and successfully kept it off followed high-carb diets.) But there's one the carbohydrates must contain a lot of fiber; another study he mentions shows that people gain weight on low-fat, low-fiber diets. The Spark is a miracle pill for entry-level exercisers, or those who've been inactive for a while. You can get started in exercise without turning over your life to your program, and continue to use sparks your entire life--which will be much longer and healthier as a result of the simple 10-minute bursts of effort. --Lou Schuler