3. Half Knee Hip and Quad Stretch

This move feels amazing and will work your
quads and your hips.
Here's How: Come onto your knees, taking your left foot out in front of
you, bending it at the knee. Slowly lift your right leg up, grabbing
your hand around your foot slowly taking the heel of your foot towards
your glutes. Hold this pose till the tightness feels relieved.
4. Quad foam roller stretch
When you sit down for most of the day, the quad muscles can get short
and tend to be under constant tension. Using a foam roller, however,
will help.
Here's How: Lie face down with a foam roller under your right leg, under
your quad. Put the majority of your body weight on your leg and roll
slowly. You can roll up and down and side to side as well focusing
pressure on the tighter spots of your muscles. Then switch legs.
Continue to roll until you no longer feel pain.
5. Hamstring stretch

The hamstring muscles affect the knee more
than we think and can be a major source of pain or discomfort.
Here's How: Lie face up with your left leg flat on the ground, keep your
foot flexed. Take your right leg up placing it against a wall, table or
using a resistance band. At your deepest point of the stretch,
alternate in five-second sequences between contracting and relaxing the
foot. Aim for 10 to 15 rounds of five-second holds. Repeat with your
left leg.
6. Straight leg raises
This is an easy strengthening leg exercise that puts little to no strain
on your knee.
Here's How: Lie face-up with one knee bent and the other leg, bent at
the knee, heel on the ground. Lift your straight leg up about one foot,
rotating your leg outward, toes will point diagonally. Do 3 sets of 10
to 15 reps alternating legs. As you get stronger, add ankle weights up
to 10 pounds.