If you have a regular fitness routine, you may prefer alternating between days of cardio and days of strength training. On your strength training days, don't just jump right into your squats and lateral raises. Do a little cardio before you lift. Warm up for five minutes of easy cardio such as speed walking or jogging, and ramp up your pace for another five minutes with running, biking, or jumping rope. It's just enough to get your blood flowing and your heart rate up, and will also warm your muscles and tendons. This increases your muscles’ elasticity, allowing you to endure a longer workout, and prevent injury.