The older I get, the more I try to find the opposite of bitterness: gratitude. When my mind starts to wonder into unproductive, black corners, I remember all the amazing bright lights of my life. Gratitude is like a magic potion to put you on the right track. It works like this:
Bitterness says, "I don't like my flappy arms." Gratitude replies, "At least you have arms."
Bitterness says, "I'm pissed that my father died when I was 16." Gratitude replies, "He loved you and at least you knew him for 16 years."
Bitterness says, "I've lost 3 good friends in the space of a year." Gratitude replies, "You had great friends and a lifetime of memories with them."
You get the point.
It is easy to wallow in misery, but it's much harder to truly look past the bad to see how incredibly lucky you have been. You still have a life to live. How can you make yourself stronger and better? How can you be the best YOU you can be? Start by using the gratitude potion. It works every time. Then, once you have your head pulled out of bitterness, you can see clearly what is front of you. You decide which direction you want to walk in. Gratitude dissolves blackness and makes you see your life honestly. The past isn't happening anymore. Don't keep reacting the rest of your life to something that happened days, weeks, years, decades ago. If you let the horror of your past lead your current course, it's like you are a primitive being standing at a bonfire alone, sticking your hand in it over and over again. You are alone at the fire, everyone has long since left you, and nobody cares you are there.