I am just reading this book Body for Life - 12 Weeks to Mental and Physical Strength. It recommends strength training 3X per week and cardio 3X per week. But the recommended Cardio is only 20 MINUTES! I have not started this program yet but I am already going through Cardio-Withdrawal just thinking about limiting myself to only 20 minutes. Has any one tried this program? Is 20 minutes enough for fat burning? The book contains many pictures with awsome results.