Do not dwell in the past, do not dream of the future, concentrate the mind on the present moment. Yesterday's the past, tomorrow's the future, but today is a gift. That's why it's called the present. Life can only be understood backwards; but it must be lived forwards. You realize that our mistrust of the future makes it hard to give up the past. Not mourn for the past, not worry about the future, live in the present moment wisely & earnestly.