Work/relationship/city sucks? Change it. Can’t or won’t? Find something else you can and will change. You might be looking for fulfillment in the wrong places. Make the choice to try some new things. It will keep you young.
Flip side: re-evaluate what you have. We are wired for novelty. Familiarity breeds contempt, as they say. That doesn’t mean where we are and what we have is bad. It could be that you’d have been blown away at half your age to meet who you are today.
Anyway these are platitudes but they’re so well-trod because everyone faces this in some form or another. People blow up their lives and have all kinds of adventures, sure. But you don’t have to blow up your life to create adventures. Just, the next chance you get to do something you’ve never done before, go for it.