I think praying is good for two main reasons:
1. It helps you forgive others; if you pray for your enemies (might be a strong word; those who harmed you?), you’ll tend to forgive them much more easily; “Love” is “willing the good of the other” (Bishop Robert Barron); if you pray for the other person, you wish them well;
2. It helps you become an actual friend with someone who did you harm; wait! There’s more than a simple forgiveness. You tend to become friends with other people.