A bit off topic, but having followed tennis for the last 3 decades, i think the most striking thing on nadal and federer compared to previous generation is how much they improved technically throughout their career, even after their 30s ( after they both had won numerous grand slams). Nadal has improved on serve and volley, federer has improved on backend and serve. Watching young federer or young nadal vs today’s is extremely impressive.
i think that it’s something we should all take lessons from, and is actually very encouraging for everyone in every field: Age limits are being pushed in every dimensions, and no matter where you are in your career, there’s always new things to learn and new limits to overcome.