Imagine carrying a backpack full of rocks all day long. Every time someone offends you and you hold onto that hurt, it's like adding one more rock to the backpack. Over time, it gets too heavy to walk.
The Bible says that wisdom gives us patience, and that it's a glory to overlook an offense, in other words, to let it go. That's not weakness, it's strength. Whoever forgives takes a rock out of the backpack and walks lighter.
Think of a friend who called you something ugly without meaning to, in a moment of anger. You can hold onto that forever, or you can choose to forgive and keep playing with them. Forgiving doesn't mean the offense didn't hurt, it means you chose not to carry that weight.
Jesus, even while being nailed to a cross by people who hated Him, asked God to forgive them. If He could forgive that, we can also forgive the small things in our everyday life.
Forgiving is taking a heavy rock out of your own backpack.