There are plenty of good reasons not to work out: job pressures, family commitments, and painfully long workout sessions that are equal parts boring and complicated.
Our solution: a three-step fitness plan backed by science but built around your life — to conquer your time constraints, speed your progress, and simplify your workouts. It's designed to increase muscle size and strength, improve flexibility and endurance, and, of course, burn fat — all in less than 90 minutes a week. Start now and you're the odds-on favorite to be fit in 5 weeks.
Once you start, adopt a 3-day standard. "You'll see most of the benefits of exercise by working out hard just three times a week," says Michael Mejia, C.S.C.S., coauthor of Scrawny to Brawny. "And that's especially true if you're out of shape."
Save one workout for the weekend. That means you'll have to fit in only two sessions between Monday and Friday.
Step 1: Keep Track
Track the ancillary benefits. Keep a job-performance journal on the days you exercise and the days you don't exercise. Each day, rate these three categories on a scale of 1 (poor) to 7 (excellent):
1. Your ability to work without stopping to take unscheduled breaks
2. Your ability to stick to your routine or plan (your "to do" list) for the day
3. Your overall job performance"It's likely you'll find that you score higher and do more on the days you exercise, despite taking time out for your workout," says Jim McKenna, Ph.D., a professor of physical activity and health at Leeds Metropolitan University, in the United Kingdom. (Make sure you compare days that are similar in workload.)
Keep your streak intact. Research shows that when men skip a workout, there's a 62 percent chance they'll miss an exercise session the following week. If you don't have time for your entire workout, take 10 minutes and do a portion of your routine — even if it's only a couple of sets of pushups and lunges.
Step 2: Go hard, not long
Cap your exercise sessions at 30 minutes, and work every muscle, every workout. University of Alabama researchers found that men who trained their entire bodies each session, 3 days a week, gained 10 pounds of muscle in 3 months. In fact, they packed on four times more muscle than and lost twice as much fat as men who worked each muscle group only once a week. Use a modified circuit routine. Do one set of each exercise in a consecutive fashion, but — unlike with a classic circuit — rest after each.
Use this simple trick to gauge the ideal downtime: "Rest between exercises only as long as it takes for your breathing rate to return to normal," says Bill Hartman, P.T., C.S.C.S., a strength coach in Indianapolis. As you become better conditioned, you'll automatically take less time between sets. This ensures that your workout is as challenging in week 5 as it was in week 1.
Finish with cardio. After your weight session, dedicate the remainder of your time to running, cycling, or rowing. Don't worry about the clock: "You'll improve your conditioning more by running at a high intensity for 15 minutes than with the slow 30-minute jog that most guys do," says Mejia.
Step 3: Keep it simple
Forget about target heart rates and three-digit lifting tempos. "Working out isn't rocket science," says Mejia. "You just need to challenge your body a little bit more each session." The keys to doing just that, without thinking twice:
Trust your lungs. In a recent study at the University of Wisconsin at Lacrosse, researchers discovered that running at a pace that allows you to talk — but only in short spurts of three or four words at a time — is approximately the same as exercising at your "ventilatory threshold," or the highest intensity you can sustain for the duration of your cardio session. By gauging your effort this way, you exercise as hard as possible without running out of gas too early.