People who say golf is not a tough sport to play are wrong. If you play regularly, or you don't use proper form, you can suffer lower back and knee pain. If you have severe or ongoing pain, consult a doctor. If your pain is fairly minor, you can try doing exercises to help. Do not work both muscle groups simultaneously. Instead, do separate exercises for each. Discontinue the exercises immediately and seek medical help if you feel any discomfort besides normal muscle fatigue. This could be a sign of a serious injury.
To stretch your back and strengthen your core, lie on your back on a yoga mat. Fold your arms underneath your head. Put your legs together and feet flat on the mat, with your knees bent 45 degrees. There should be a small gap between the small of your back and the floor. Contracting your abs, press your pelvis into the floor until you've closed this gap. Hold this position for five seconds. Exhale and release. Do a set of eight presses.
For a lower-back stretch, lie on your back with your legs bent, as you did for the pelvic press. Instead of placing your arms behind your head, place them at your sides, palms down. Slowly raise your hips off the floor until you've lifted them at least 6 inches. Stop as soon as it feels uncomfortable or when you reach 12 inches off the floor. Hold the lift for five seconds. Lower down slowly. Inhale when lifting and exhale when lowering. Do a set of 16 lifts.
Knee Pain Exercises
If you injure your knee, there is no specific exercise that will help make the pain subside. The Mayo Clinic recommends a treatment of rest, ice, compression and elevation. As soon as your knee is well enough, start working on strength and stability. You can't strengthen the knee itself, but it will benefit from your exercising the muscles around it.
Do leg lifts to strengthen your quadriceps. Lying on a mat with your arms at your sides, stretch one leg out straight along the floor. Bend your other knee 90 degrees with your foot flat on the floor. Lift the straight leg up until it reaches the height of your bent knee. Hold for three seconds. Lower. Do 10 lifts for each leg.
Try balance exercises to increase knee stability. Stand up straight with both feet pointed forward, legs together. Place both hands on the back of a chair to support your body. Lift one foot off the ground and bend that leg at the knee so that your heel meets your buttocks. (It's okay if you can't bend it quite that far. Just do the best you can.) Balance on the other foot for 10 seconds. Practice this exercise daily until you can balance for at least 30 seconds without using your hands to support you.