If your calves are extremely flexible, you may need a deeper stretch. Try the Advanced Calf Stretch. Because this stretch is relatively aggressive, you may need to build up to it by practicing the Traditional Calf Stretch first.
Place both feet as close as possible to the edge of a step or curb while maintaining good balance. If possible, use a tree, pole, or even another walker for balance.
While keeping your rear legs as straight as possible, lower your heels over the curb as much as feasible. You achieve the best stretch by hanging as close to the edge as possible and lowering your heels as far as they will go. After holding the stretch for 20-30 seconds, alternate legs. If you still feel tight, repeat this stretch more than once.
This stretch is also effective if you stretch one leg at a time. The stretch is performed in the same manner, just tuck your non-active leg for balance.