Do you ever wonder what exercise you should be doing? There are so many to choose from. Today, I'm going to give you a list of activities, how many calories they burn, and what part of your body they help. For illustration purposes, I'm using a person who weighs 150 pounds. Biking: According to WebMD, “leisure biking” is going at a speed of less than ten miles per hour. If you do this for 20 minutes, it burns 93 calories. However, leisure biking is no joke. My bicycle only goes to 7 miles per hour, and sometimes that isn't so easy to do. On the other hand, 20 minutes of mountain biking burn 193 calories. Mountain biking is much harder to do, so if you haven't gotten to regular biking, I would recommend you start with that. Either way, both forms of biking are going to work your legs, and are good for marathon training. Mountain biking has an added advantage: You're biking uphill, so your arms will be more involved, which helps build muscle. Jump rope: Everyone did this at some point, probably during gym class in elementary school. Remember Jump Rope for Heart, the fund raiser that the American Heart Association would put on every year? That wasn't just to keep us occupied, jumping rope really has health benefits, especially when it comes to cardio. 20 minutes of jumping rope burns an astonishing 227 calories. Because you're lifting your arms during each rotation of the rope, your upper body is going to get a very intense workout, and this is a great way to burn muscle. You're also getting your heart rate up, because of the jumping, which is going to strengthen your heart, and burn a lot of calories. Swimming (Breaststroke): All around, swimming is one of the best exercises any person can do, providing they know how to swim. The breaststroke is just general swimming (like they do in the Olympics), where you're on your stomach. This is working your arms, legs, and heart, all at the same time. So, in some ways, this is the ultimate workout (have you seen the muscles on professional swimmers?) 20 minutes of this burns 227 calories, the same amount as jumping rope. Personally, I'll always opt for something aquatic.