My personal feeling is that around 40, your new skill gathering has not declined too much, yet you have a ton of experience which helps you with analogies and e

My personal feeling is that around 40, your new skill gathering has not declined too much, yet you have a ton of experience which helps you with analogies and enforcing connections in your brain. I got my masters in late 30s and it was much different than for people doing it in early 20s. That is I did most of the learning by analogy, drawing from my own experience, but I had a hard time with lot of minutia which was much easier in 20s. It certainly felt my blade had dulled and still feels that way (and is not going to get better!). Also, I am still waiting for examples of people taking up a completely new skill in their 30s or 40 and reaching proficiency of those who started in their teens. So far I have not found any. The best has been someone in their late 20s starting to play chess and becoming a master, when they were already holding high dan at shogi.