That would be...understanding earlier that karma is not some bloody boomerang that goes around and comes around. The brutal reality is..."What you do to others...stays with you.". If my ass lives in a glass house and so do you...then I can't break your windows to get to you...without violating the integrity of the house I live in. Took me awhile to understand what the Chinese meant when they said..."When you go for revenge...dig two graves." Now I do.
I must be perfectly blunt...if only for myself...that too often, what I do is not for the right reason. Much of it is simply because I just do not want to pay the price...because of wrongdoing ...for the things that will stay with me. Whenever try to ignore this hard learned lesson...it comes to me quickly that already the price is too high to bear and I back down.
There are others...but this jumps first to mind. Peace and blessings to you and yours.