You're in your late 30s and it used to be OK. But one day it hits you that you no longer feel the same way as when you were 25. The things you enjoy and get excited about suddenly loses their thrill and you just can't muster enough energy to sustain your effort pretending that you like it.
Am I entering the what so-called "life begins at 40?" In a nutshell, loosely quoting Meryl Streep "when you become 40, you do not give a shit".
It's hard to accept but I guess that's how life is. Everything feels so temporal and quick that even you somehow force yourself to think that you'll always gonna be the same and the feelings will remain the same you still wake up one day and feel that you are a completely changed person. No bargaining. It's a done deal.