We all know the downside of lounging on the couch all day. We watch too much TV and don’t get the exercise we need.But there is the occasional downside to being more active than your puppy. This guide will help you decode very common injuries and muscle aches, so you can figure out how to help heal your body and feel more beautiful.QUIZ: Do You Have a Healthy Exercise Routine?Plantar FasciitisThis is the most common injury, and it’s not just a condition that affects intense runners. It results in intense pain in the foot and heel. You’ll have a lovely-looking limp, to boot. The plantar fascia is a thick bundle of tissues that runs from the toes to the heel on the bottom of your foot. When the tissue gets overworked, it creates tears in the fascia. This results in inflammation and pain, mostly near the heel.There’s not a lot of blood supply to this area, so the healing can be slow and frustrating.This typically occurs because you roll the front of your foot too far to the inside (overpronation of the forefoot). This feels like severe bruising on the heel. It usually feels worse in the morning, when you first put weight on it.To stretch and strengthen the area, sit in a chair with your affected foot crossed over the other leg, so your ankle rests on your knee. Grab your toes and bend them upward, toward your shin. This stretches the fascia to relieve or prevent some pain. Make sure you have good running shoes to control the overpronation. Rubber-soled shoes and cushioned heel inserts can help. You may want to take anti-inflammatories.VIDEO: Anatomy of a StepAnkle SprainsThese make up 20 percent of sports injuries. It’s no surprise, as the outer ankle ligaments aren’t very stable. To recover, you should include strengthening exercises. The aim is to regain full range of motion. You can do this by bending your ankle in all four directions, and then doing so while pushing against it in those directions.You’ll need to strengthen the surrounding muscles and ligaments as well. This includes the dynamic stabilizers of the joint, like those in the back of your ankle. Proprioception—knowing where you and your limbs are when you move—also helps you regain motion. Practice walking with your eyes closed.ACL Strains & TearsIt’s not just skiers and football players who tear the anterior cruciate ligament of the knee. A lot of people are doing it. Menstruating women do it eight times more than others. Why? Two reasons. Women have wider hips, so the angle of the femur into the knee is sharper. This makes them prone to putting more torque on the ACL when they start and stop abruptly. Also, during menstruation, progesterone and relaxin hormones cause the soft tissue to become like a wet rubber band—more likely to rupture.It’s important to build the muscles (hamstrings and quadriceps) around the knee to keep pressure off the ligaments. This way the muscles take some of the force when you’re in motion, instead of the joints.Achilles TendonitisThis happens when you torque your Achilles tendon, which connects the two large calf muscles to your heel. This usually happens when you rotate the foot and knee in opposite directions. This tendon is the strongest and largest in your body, and can withstand a 1,000-pound force. It becomes particularly vulnerable when you increase training dramatically, or fall into a hole. You’ll need demobilization and/or surgery after a tear. If you stretch and warm up the area, you can reduce the chance of inflammation and tears. Wear good, stable shoes, too!MORE: Exercise & Your Appetite: The TruthHamstring PullThe hamstring is a group of muscles that attach to the lower leg and support the hip joint. It becomes injured by overuse—particularly over-striding during a run. Scarring of injured areas creates more tension, making re-injury rates about 80 percent. This is why it’s especially important to stretch after a warm-up. Put your foot on a chair and lean forward, while bending at the hip until you feel hamstring tension. Switch legs after holding for a minute.Groin PullYour inner thigh muscle (adductor muscle group) lies between the femur and pubis bone. This is vulnerable to tearing when you overexert yourself or your muscle is cold. Stretch and strengthen the area by lying on your back and spreading your legs (butterfly position). Allow your knees to fall apart so you feel the stretch. Place a ball between your legs and squeeze to strengthen.Rotator Cuff StrainThe rotator cuff consists of four muscles and their tendons, which originate from the scapula and form a cuff over the upper end of the arm. This head of the humerus is your shoulder joint. The cuff helps lift and rotate the arm and stabilize the humerus within the shoulder joint. It’s vulnerable to tears after a fall or repetitive overhead arm activities. Strengthening the area will help prevent injury. Never lift weights without being able to see your hands.