This move stretches the quadriceps, the large muscles on the front of the thighs. Stand facing the back of a chair (a wall or a tree also works). Using the left arm for balance, bend the right leg and grab it with the right hand. Gently press the foot toward the buttocks until you feel the stretch in the front of the thigh. Hold and then switch legs.
You can also do this stretch with opposite arm holding opposite foot. It is slightly more challenging to balance this way.