If everyone could just do one stretch exercise this would be it, because a tight calf can really affect your gate and posture. Tight muscles in the lower leg can cause your spine to pitch forward into a hunched posture in every step you take. Do this stretch to find out if your calves can be increasing the load on your spine.
Put a half dome or a tightly rolled-up towel on the floor. Put the ball of your right foot (fore-foot) on top of the half dome then lower the heel all the way to the ground. Then take a step forward with your left leg while keeping your pelvis and feet facing forward square with your shoulders. If you have good calf mobility you should be able to step well in front of your right foot while the right heel stays on the ground. If the calf is tight you are likely to want to compensate by lean/bend forward from your hip or spine to compensate for this tightness. This postural adaptation is also what happens when you walk around with tight calves on a daily basis which puts a lot of strain on your lower back. Hence try to avoid this bent forward posture during the stretch. Aim to stack your shoulders vertically plum over your hips and your head over your shoulders in a tall relaxed posture. Also, focus on keeping your thigh and kneecap relaxed. Keep working this stretch until you can do a full stride length step while the forefoot is on the dome, the heel on the floor, and a good neutral posture is maintained. Hold the stretch for up to 60 sec and repeat 3-times a day for the best result.