Hamstring (back of the upper leg) stretch.
Stand upright, with your leg straight and your foot resting on a stair or low stool in front of you. Exhale, and slowly lean into your straight leg until you feel a comfortable stretch. Hold for 10-30 seconds and return to start. Repeat on both sides, several times.
Calf (back of the lower leg) stretch.
Stand facing a wall with your toes almost touching it. Lean into your hands placed at shoulder height against the wall. Move one leg back only as far as you can keep that foot flat on the floor, but far enough that you can feel a comfortable stretch in your calf muscle when you lean into the stretch. Keep your toes pointing straight forward. Repeat on both sides, holding for 10-30 seconds.
An alternative calf stretch.
Place the ball of one foot on the edge of a step and lower the heel off the step. Hold and stretch the calf muscle for 5-10 seconds. Stretch one calf muscle at a time, alternating legs. Repeat at least 10 times each.
Quad (front of the upper leg) stretch.
Holding onto a table or back of a chair, grasp your foot or ankle. Let your knee dangle straight down. Without leaning forward, move your knee backward to a comfortable stretch, hold for a few seconds, and then return. Repeat on both sides up to 20 times.