You know your body aligns and tenses in a different way when you try to push the ground away in a push up or try to push yourself off the ground. You can work this to learn to relax more and to align in the upright position by squatting slowly with your hands in front of you and someone either pushing your hands up or down or to either side. This forces you to adjust your spine muscles (the one erecting and moving the spine) according to the tension and allows you to become aware of a lot more and learn to control your posture and tension swiftly. You can do the same with big rubber bands or anything heavy around you.