Stand and let a partner or two come at you in walking speed. Place your fist or hand on him relaxed and let his movement coil the springs that are your arm tendons and joints. As you feel charged or feel he is too close for comfort you feel through your contact where you can give this pressure back and send him straight backwards. As the pusher you need to relax all the parts of your body not involved in the work so you keep free and mobile and as the pushed, you need to work on your relaxation so you don’t attach too much meaning to the push and keep your legs and hips free so you don’t trip or stick yourself in some weird position as you fight the pressure instead of letting it pass. After you can send him forward in walking speed add more motion to this and have him come at you with any strike or grab he chooses. This way you learn to work without getting engangled in a fight and your temper and ego must also remain calm. Now slow down again and as you move the arm work on spinning him or sending him in one direction or another and this gives you move control on your actions and helps a lot in delivering strikes and working with masses. Breath naturally and keep the face relaxed as you work.
Do the same work as both of you are walking or one walking and the rest running at him and enjoy the contact