I think many people long for years when they were young, pretty, full of energy, good health, hopes and ideas, and everything was possible. They had people around, friends and families. At old age, the health is gone, your friends and relatives are dead, and world around you is different than the one you grew up. If I would ever travel back into times, I would love to get around 1984 when most of my relatives was alives, could go to best ice cream store in town which closed down, where we had neigborhood of old homes that were torn last decade to new shopping center. This world is gone.
Old Czech proverbs say:
"Young people have death behind their back, old people in front of their eyes"
"Young people live for their hopes, old people from their memoirs"
"Time builds castles and time demolishes them"