Don’t use up all your cognitive energy living in the past or the future. The part of time that really matters is NOW. It can be good to look at the past to see where you have been and how far you have come, and good to look to the future to figure out what where you want to be and what it will take to get there; you don’t want to spend all your time in either place. The only time we really have is now; it is important to live fully in the present. You can’t do anything in the past or in the future. You can do things only in the present.