or possibly have untreated depression

Ha. That's how I was with Saxophone. I was near pro level, and had to decide if I wanted to go to college for music or a more practical major. I chose comp Sci, picked up the guitar, and refused to take lessons or follow any kind of lesson plan for it, because I wanted it to stay "fun".

20 years later, I suck at guitar and forgot the Saxophone.

Before long you meet a violinist who drags you into a competition, and rediscover your love of playing piano just before she leaves forever

At least that's what I learned from anime

Coffee stain? Is this what all the cool memes are doing?

It really does feel like we're not really built for doing more or less the same thing, for most/half of our days, for 40+ years.

That's why I'm a professional Data Manager and not a Software Developer. I love programming too much to do it 8h a day and so I just do data stuff.

I'm sure some people are able to keep it fresh.
It happens in art, where some musicians are able to keep challenging and reinventing themselves. It happens in sports - I've read about it in baseball articles - where athletes who maintain a level of excellence beyond their early thirties talk about how they had to find a way to re-motivate themselves.