Pain is opposite happiness, but are not exclusive. One cannot exist without the other. Happiness without first knowing pain is empty and shallow. Pain gives happiness its worth. Pain is a tool used to teach. Unfortunately, pain is often misused. It is often ignored. It is often held onto. It is often run from.
Ignoring pain is like being a jar shut tight. Trying to look fine from the outside while spoiling and rotting from the inside. We refuse to open the lid and expose the pain because we are afraid of the stench inside that is only growing worse as it sits. Jars are brittle and break easily. It only takes a small push to send a jar falling down to shatter. Leaving a mess of spoiled inside and sharp glass strewn across the floor.
Holding onto pain is like being a time traveler stuck in the past while the present continues on without us. 'Time heals all wounds' is often said but is often wrong. Time alone is a tool. Tools cannot fix or heal without being used by a person. Time used heals wounds. Time abused festers wounds.
Running from pain is like trying to run a marathon on a treadmill while chained to the treadmill. We run and we run but do not get any farther from the start, or any nearer to the goal. Pain has the key we need in order to get off of the treadmill and to make progress to the goal.
Open the lid. Set the TARDIS to present. Take the key. Be free.