You may hurt yourself if you stretch cold muscles. So before stretching, warm up with light walking, jogging or biking at low intensity for five to 10 minutes. Or better yet, stretch after you exercise when your muscles are warmed up. When you're stretching, focus on major muscle groups such as your calves, thighs, hips, lower back, neck and shoulders. Hold each stretch for about 30 seconds; in problem areas, you may need to hold for around 60 seconds. Breathe normally as you stretch. Expect to feel tension while you're stretching, not pain. Stretching can be time-consuming. But you can achieve the most benefits by stretching regularly, at least two to three times a week.