It’s one thing to get upset over an injustice you suffered at the hands of someone else, but it’s another thing entirely to hold on to that emotion long-term. That’s called holding a grudge and it can easily consume you if you’re not careful.

The reason this is so bad for your happiness is because the negative emotions associated with grudges eventually give way to resentment and thoughts of revenge. In turn, this leaves little room in your emotional repertoire for anything else, like happiness, according to the Mayo Clinic. What’s more, decades of research have linked this simple act to better overall heart health, less psychological stress, improved physical ability, and longer life.

That’s why it’s always better to forgive and move on than hold on to a grudge.