Past 25 I started to realise I couldn't remember everything that everyone had said to me. This was also around the time I developed a social life, so it could just be that my brain had more to manage socially.

Past 30, I stopped caring about appearances so much and started working on developing mental skills. I was able to defend my beliefs better, make more on-the-spur jokes.

Past 35, I no longer care about anything. I have bouts where I'm in interested in building things, or conversing. But now? Eh, work/sleep is enough.