When people get old
When people get old “I think people get old when they stop thinking about the future. If you want to find someoneʼs true age, listen to them. If they talk about the past and they talk about all the things that happened that they did, theyʼve gotten old. If they think about their dreams, their aspirations, what theyʼre still looking forward to – theyʼre young.ˮ | Peter Attia, Outlive
This makes future optimism a measure of intellectual age. Physical age doesn't track in this way.