Another point to consider is the distance between you and your target. If you need to lean forward to touch than you are rather tense already without even lifting your arms and legs. Consider taking that little step and work from a comfortable distance which again changes with every heartbeat and every breath.
When we breathe and move it is a long line of levers and pulleys which lets the movement happen. If you want to place your fist in someone’s stomach than think of the least amount of levers you have to work to get the job done and than the energy will move better with less tension and more awareness of where the door is open for you to enter. For example work with the wall or with a partner on reaching it with the least amount of tension in your arm or leg or any part you have and you can move. You can have a belt tied around you or a partner hold you and you check where your body can go and what is the simplest way to get the job done. Find different ways to reach your goals because we are always changing and what you worked with a moment ago is never to return.