One of the challenges of good coaching is to keep your words positive. When you see someone doing something that we want to correct, the words “bad,” “wrong,” or “here’s the right way,” can easily pop out. Such negative feedback invites resistance and defensiveness. We at SSA recommend avoiding words that invite resistance. Instead telling the person what they are doing wrong, describe to them what you suggest will be a safer or stronger technique. (“Try moving your elbow in just a bit and see if you feel less stress and more strength.”)
Instead of saying “You’re not standing in your line of power.” Say something like “Try moving your left foot forward to get closer to your line of power. See if that takes some of the strain off your back.”
It may take a bit of practice, but turning negative feedback into positive suggestion is usually not too difficult. the reward is a person who will be more open to your coaching suggestions.