Whether it's cold and raining or plain too hot, you may come up with a lot of excuses to not go outside for a run. Yet you know you need to work on your cardio, either to stay in shape or lose that last bit of pesky belly fat. It is not necessary to run dozens of kilometres to strengthen your cardiovascular capacity. Instead, try out this five exercise circuit you can do from the comfort of your own home:1. Jumping jacks - 30 secondsTip: Make sure to reach the full range of motion.2. Mountain climbers - 30 secondsTip: Remember to keep your butt down.3. Skater Jumps - 30 secondsTip: Remember to really engage the supporting leg.How to skater jump Men's Health4. Blast offs - 30 seconds Tip: Remember to maintain good form throughout the entire movement.5. High knees - 30 secondsTip: The higher your knees and the faster you go, the harder your lungs will work.Coach's tip: Remember to maintain a good pace so you don't run out of breath too quickly.Number of circuits: 3\/5\/7 depending on your level.Rest: 30 seconds between each exercise. Try to maintain the pace throughout all the circuits.