Don't hold grudges. Practice forgiving people.
I can't believe how many people I meet who don't speak to their mother, father, sister, brother, etc. We all have flaws, and even if the other person is in the wrong, approach them and seek peace. When you hold onto a grudge, you punish only yourself.
Forgiving people is freeing. Try it.
Also, have time every week where you do nothing but sit outdoors with your thoughts. Even if only for a few minutes.