Whether you're running, biking, or swimming as your form of cardio, you want to get the most out of your workouts. When some people are training, they incorporate negative splits into their routines. It involves moving faster in the second half of your workout than you did for your first half. This warms up the muscles slowly, which helps reduce your risk of injury, and it also helps you finish strong when you're racing.
You can also work out in the opposite way, where you start off fast and intense and end your workout slower and with moderate intensity. Researchers at the College of New Jersey found that after a short warmup, "cyclists who punched up the intensity during the first half of their workouts and then cruised for the second half burned about 10 percent more calories than those who started slow and finished fast." Not only will you burn more calories, but when you give it all you've got in the beginning, it feels so good to reward yourself with a more relaxed second half of your workout.