Do not brood over your past mistakes and failures as this will only fill your mind with grief, regret and depression. Do not repeat them in the future.

What does it mean to brood over?

to think and worry about something a lot. brood about/over: Don't sit and brood over it for weeks. Synonyms and related words. To worry or feel nervous about something.

What does it does not brood over injury mean?

Love does not brood over injury. I would analyze the meaning of the word, "injury", as used here, to mean: hurtful words or insensitive behavior to your wants and needs. "Brood" used in the context of this thought, then, would mean to agonize or worry too much over what someone you loved said or did to you.