The Ball in the Box metaphor can help people PTSD and grief. Whenever the ball bounces against the sides of the box you feel the painful memory of your grief or trauma. In the early days the ball is almost the same size as the box and so you are triggered almost constantly. Over time the ball diminishes in size and so hits the sides much less frequently. Consequently these episodes happen more unexpectedly and take us by surprise; like a remembered song or smell. The ball will always exist and may grow and shrink during different periods of your life, but knowing these triggers are going to become less frequent can help you manage those days when the ball is all consuming.