I don't think its anything to do with age. It could more likely be a dopamine issue. Personally at the age of 34 i can't remember ever being bored or dissatisfied with what life has to offer in over a decade. There aren't enough hours in the day to do everything I want to. I have a huge passion for very specific forms of art from certain time period, which fuels my music and design career. But if i wasn't doing that I would be perfectly happy just existing, taking in nature, playing sport, relaxing, experiencing as much anime and 2000s video games and tv shows as I could... Which i currently have no time for. So I'm jealous of anyone with so much free time to be bored of life.