Feel as if the chair or the floor, is supporting your whole weight and that it is safe to let go. Imagine a pleasant place and feel as if you are really there and rest a while. You must exercise to ensure a strong heart and circulation and it is a good way of relieving tension. Remember to have regular Medical Checks. Swimming walking and cycling are probably the best, but any exercise is good.
Movements combine with relaxation.
It is great for taking your mind off your problems too.