If you are new to exercise, aim for 30 to 40 minutes of cardio during Phase One. If you already exercise regularly, aim for 45 to 75 minutes. If you’re too busy to do it all at once, split it into 15-minute sessions — a brisk walk before work, another at lunch and one more after work will do the job. For the weight lifting you’ll do in Phase Two, you can get an intense, full-body workout in 20 or 30 minutes if you know what you’re doing. If you’re just starting out, a personal trainer or group strength-training class can help you get up to speed. Get creative! You can check out workout videos from the library to keep things interesting. And be sure to keep your exercise phase-specific: Cardio during Phase One, weights during Phase Two, and relaxation/stress relief (like yoga or meditation) during Phase Three.