I don't think this diminishes your point, but, for a thing like memory, your father may be maintaining it by insisting on relying on it. It may diminish regardless, but its diminishment may slow down.

At work, we are in a certain kind of race. In life, we are in a certain other kind. To paraphrase a recent Brandon Sanderson talk about creativity in an era where AI can outpace and possibly soon, out-quality a professional, "The work you do on _you_ can be _the art_."