Repeat the statement “I forgive myself for not understanding” in your heart.
Repeat it over and over.
After some time, you will notice memories come up. Painful ones. Once they come up, you need to address them.
Let’s say you remember a time when you made a mistake. Mentally repeat: “I forgive myself for making that mistake.”
You may notice your mind complain at first. Mentally repeat: “I forgive my mind for not wanting to forgive.”
Then, go back and repeat the statement: “I forgive myself for making that mistake”.
Make sure to relax as it happens. Relax your head. Relax your face and jaw. Relax anything that is tensing because of the memory.
Experiment with it. Find words that work for you. Words that evoke a warm heart. Relax in a way that works for you. Play with it.
Now, let’s say that a new memory comes up after you’ve resolved the first that reminds you of someone who did something to you.
You repeat: “I forgive you for not understanding.” or “I forgive you for not understanding how you caused me pain.”
Genuinely. Sincerely. Wholeheartedly (to the extent you can) forgive.
You can do this anywhere. Anytime. And every time you do it, those memories will plague you less and less. Leaving you a pure and clean mind.
After doing this for a while, transition into mentally asking for forgiveness for others you've hurt. (Please forgive me for not understanding.)