Whether your goal is to make it around your local track once or to compete in a marathon, top personal trainer Tom Holland has a message for you: Keep it simple. "The flashy stuff may look great if you're trying to show off at the gym, but when you really want results, you've got to get down to business with simple, high-energy moves that get the job done," the fitness superstar said.

Holland has more than 20 years' experience working with thousands of clients who range in fitness level from the basic beginner to the professional hockey player. In that time, he has found that working as much of the body at once with straightforward, anyone-can-do movements is the way to go. One of his favorite routines is called the Super Circuit ‑- that's where you alternate fast-paced cardio intervals with muscle-toning strength exercises. According to Holland, it's a workout that gives you a lot of bang for your buck because you get your heart and lungs pumping, tone every muscle in your body and incinerate a ton of calories. Not bad for something that only takes 20 to 45 minutes, three times a week.

Holland has designed this boot-camp-style iVillage Super Circuit to fit into any fitness program. "You can do it even if you're just starting out or even if you're really fit and looking for something quick yet challenging," he says. His recommendation: Do this workout two to three times per week, alternating it with less intense choices such as walking, jogging, cycling or swimming. You'll burn at least 200 calories in 20 minutes, which gives a real boost to any weight loss program. And in just four weeks, you'll have a tighter, firmer, more sculpted body.

• The Workout
• Cardio Intervals
• Strength Moves