Most guys don’t give much thought to body weight workouts, but some of the toughest exercises I’ve ever done have used only my body weight. The two that come to mind immediately are the Pistol Squat and the 1-arm push-up. You have to be very strong and fit to do either of those exercises.
If those are too advanced for you, you can try 1-leg Squats (only going down half as far as the Pistol Squat) and Decline Push-ups (elevating your feet on top of a second stair of a staircase).
There are also a lot of abdominal exercises you can do with only your body weight, and I don’t just mean crunches. Better exercises include planks, side planks, mountain climbers, and cross-body mountain climbers. Those are all total body ab exercises and are not as hard on your low back as sit-ups and crunches.
You don’t need a cardio machine to burn calories. For years, my clients have been using body weight circuits for interval training. Most body weight exercises are the perfect hybrid of strength training and interval training, and unlike cardio machines, they don’t put as much repetitive stress on your joints (from doing the same thing over and over again) and they help improve your athletic mobility. Body weight exercises and workouts are a much better way to train than with machines!
