We are three travelers: past, present, and future selves. Rarely do we think of them as the same person.

In Christmas Eve on the Desert, Harrison R. Merril reflects on the connection between the three. Let’s extend Merril’s terminology and call them Past Self, Present Self, and Future Self.

First, his Past Self. A younger man—a boy, he calls him—who lived life in the moment. I know his philosophy well. Carpe diem. “Eat, drink, and be merry, for tomorrow we die.” It may only be one marshmallow, but it’s a sure thing.

It’s easy—and very understandable—to live for today. Each day can be a challenge to survive and all our focus will go there. Without a connection to the vision of what our future could be, we take no thought for the morrow and drift wherever the current takes us.

Take therefore no thought for the morrow: for the morrow shall take thought for the things of itself. —Matthew 6:34, KJV

Then Merril has a powerful realization. Not only is he—his Present Self—defined by the sum of the choices his Past Self has made, but that chain of causality extends into the future, too. The fate of his Future Self is determined by his Present Self.

No matter what choices his Past Self made, Present Self has the power to intercede and make a different decision. He can change the course of his life. He can make choices today that will free his Future Self from the ruts of the past and set him on the star-bound trail.

Our Present is determined by the habits we developed in the past. Fortunately, habits can change. We can make new habits. Unfortunately, it’s not automatic.

My mother tried to teach me how to play the piano. If I knew then what I know now, I’d have made more of an effort to learn. The haunting thing about that sentiment is that it doesn’t expire. It could follow me for the rest of my life. “If I knew at 20 what I know at 30…” “If I knew at 30 what I know at 40…” “If I knew at 40 what I know at 50…” The pattern has held true so far.

It’s never too late to change, and the change is never too great. Scrooge made the decision to change his life overnight. Everyone thought he was too far gone, but he became as good a man as the old city had ever known. You can decide right now that your future is not going to be determined by the script Past Self wrote.

See your present choices in terms of what they mean for your Future Self. “If I wait for the second marshmallow, I’m only uncomfortable for 10 minutes. In 10 hours, it’s not going to make one bit of difference. But in 10 years, I’ll be the kind of person who can say no to short-term impulses and do the hard thing to enjoy lasting rewards.”

Don’t worry about the bad decisions you made when you were younger. You were a different person then. You’re a better person now. Wiser and stronger with more experience.

The first step in changing your Future Self is realizing that you have the power to choose. You can’t change the choices you’ve made in the past, but you can change what you do about the past. Are you going to let your past be the story of your life? Or just your origin story?

Your Present Self is the sum of the choices your Past Self has made. The same can be said of your Future Self. The only difference between Past Self and Future Self is your Present Self. You—right now, reading this—you’re the key to a better Future Self. You make the difference. You don’t have to change much to have a powerful effect on your Future Self.

You’re never alone. You’re in this together. Early on, your Past Self was an idiot. Over time, your Past Self starts to learn from your Present Self and begins to do everything they can to help. Your Future Self is cheering you on. The ball is in your court, Present Self. Go forth and conquer.

Question: What will your Present Self do to set your Future Self up to be the person you want to be? Share your thoughts in the comments, on Twitter, LinkedIn, or Facebook.