The past is history, the future is a mystery, so all you have right now is the present. I cannot express to you enough the importance of living in the moment- which is actually a harder task than it may seem. It might sound silly to be preaching about something so obvious because technically everyone physically "lives in the moment," but not psychologically.

As humans, it's natural to let your mind wander back to situations from the past and re-trigger emotions of anger or sadness. However, you can't let this affect your present day life and happiness. If someone hurt you, forgive and forget. I promise you it's way harder to hold a grudge than to just move on and be happy in the moment.

This also applies to worrying too much about the future(guilty). You never get now back, so I suggest living every moment to the fullest. For example, let's say that you're in a relationship that's going super well and you are nothing but happy around each other. Then, one day, you start freaking out about where you will be a year from now, and suddenly all you can think about is that the future of your relationship is doomed when there wasn't even a significant fight or misunderstanding. It's not a good idea- trust me.

Why waste time dwelling on the past or fixating on what's going to happen in weeks, months, or years from now?

Live in the moment. The present is the only thing you are in control of right now, so I suggest that you take advantage of it. Don't waste your time with "what if's" or "what could be's." Be content and confident with what you have right now, and make the most of the cards you are given, and I promise you will be happier.