Summarize this article in one sentence.
There are certain exercises that are recommended for people who have suffered an MCL sprain. However, it is important to talk to a physical therapist before you try any of these exercises; if you begin these exercises too soon after your injury, you could cause further damage. Assume a lying position with the injured knee in a bent position. Keep your foot flat on the floor and slowly slide the heel in the direction of your buttocks as far as you possibly can without it hurting. Repeat this exercise 10 to 20 times. Grasp the right foot with the right hand and gradually pull the foot up then behind your back, towards the buttocks. Reach as far as possible until a stretch is felt. Maintain this position for 10 seconds then return your leg to the starting position. Switch to your other leg and repeat the exercise. In a standing pose, position one leg in front of the other leg. Bend the back knee while keeping the front knee straight. Place the weight on the bent knee and then lean forward. Stop once a stretch is felt at the back of the thigh . Hold this position for 5 to 10 seconds then return to the starting position. Switch legs and repeat the exercise. Exercises and muscle movements promote good blood circulation and oxygen distribution to the affected area, thus speeding up the repair of the damaged tissue.

Summary:
Go see a physical therapist. Try a heel slide exercise. Practice a quad stretch. Do a hamstring stretch. Understand why exercising your knee is important.