> So please give me a break with this idea that you are old at 60 in 2024

Well, brain decline is documented and starts well before 60, but maybe we're not equal. I'm 50, and I can tell my mind isn't as sharp as it used to be. My memory isn't as good, and I feel complex mental tasks require more energy. It seems I've lost a layer of cache. That being said, I'm not done yet, I'm still able to do my job (SWE in a competitive environment where my colleagues are much younger).