A Better Body in 2 Hours a Week: A Total-Body Workout

How Hard Is Hard Enough?

Scientists define "vigorous" activity as anything with a metabolic equivalent (MET) intensity level greater than 6.0. Your MET can range from 0.9 (sleeping) to 18 (running at 10.9 mph -- a 5.5-minute mile). Try working these vigorous activities into your routine.

• Running: Add some stairs and boost the burn by about 90 percent.
• Biking: Cruising around doesn't count. You've gotta be doing at least 12 mph.
• Step aerobics: One set of risers (6 to 8 inches) is plenty to get your heart rate pumping.
• Jumping rope: It doesn't matter how fast -- just keep jumping. If you're not feeling coordinated, ditch the rope and circle your arms.
• Boxing: Want to get more out of it? Imagine that the punching bag is your ex-boyfriend.
• Tennis: Lose the partner. A game of singles burns about 33 percent more calories than doubles.
• Soccer: Playing goalie? Jog in place during the game (that is, when the ball's not coming your way).
• Swimming laps: Try alternating strokes between butterfly, backstroke, breaststroke, and freestyle to maximize your calorie burn.
• Backpacking: Carry more than 10 pounds and you'll blast about 7 percent more calories.
• Canoeing: You don't have to be an expert, but try to row at 4 mph or faster.
• Mountain climbing: Not the adventurous type? Walk hard up a big set of stairs and get about the same heart-pumping (though not as thrilling) effect.
• Roller-skating: Pick up a pair of in-line skates instead -- you'll up the intensity by about 71 percent.