To get a better sense of how hard your heel is striking the ground and to tell if you are controlling the downward phase of the hiplist, try using earplugs! When you wear earplugs you might be able to hear the reverberation caused by each heel strike. If you are falling hard onto the next foot, it will probably seem pretty loud. If you are controlling the descent of your hiplist, your heel strike should be much quieter. For fun, try to walk silently.