A nice humbling way to teach yourself to receive and give (in that order) strikes can be this or a variation of this drill. you take the arm of your partner and he relaxes the arm and shoulder so only the form of the fist (just form no clenching) and the alignement of the wrist and elbow is kept. Now start to free the arm using yours and slowly start to use the arm as a ram to hit you in different valocities and places. You may find it silly at first but it works to give your body the feeling of being struck by a relaxed fist like a hammer and gives your parner the experience of hitting without tension so his body can learn to relax more and “give” more to others so they can learn too.