I was subbing at the school and had a class made up mainly of seniors. They kept talking about the last year of football, the last dance and the last chance to make the most of their school experience. They knew they would have only one senior year of high school. They could never go back and re-do it. They wanted to experience everything this year had to offer.
The same is true with our own lives. We each recognize that we had only one senior year of high school; but we also had only one junior year, one sophomore year, etc. Later, we had only one year where we turned 22 or 34 or 59. We can’t go back and re-live those over again. What we did with those years is in the record books for all eternity.