Gautama the Buddha was among the first religious or philosophical teachers to discern the truth that "everything changes." This prescient insight, now embedded in the standard model of modern physics, is one of the most enduring legacies of the Buddha's teaching.
When I ask audiences what they like about being older, people often answer "Gratitude," and then say what they are grateful for: grandchildren, good health, free time, wearing what they want, the chance to travel, giving back to the community.
Regret is a universal quality of aging; each of us has a collection of regrets by the time we are in our forties or fifties. Younger people have regrets too, of course, but for the young there is always the sense that there is time to start over, to try again, to reverse ill fortune.
What will we do with this extra gift of years that modern life expectancy has offered us? Enjoy it as much as possible, and share that joy, because the younger generations coming up behind us need our example and our encouragement.