Gravity, my reply is autobiographical, and I'll try to be brief.
I'm 77 years old. A daily focus of my life is daily study of harpsichord, especially the music of Domenico Scarlatti. I'm a late learner. my intention is to be able to play much of this music well and joyfully.

I have a lot to learn. Eyes must follow and decode the score, solving problems of which fingers must do what, and giving instructions to the fingers, listening to the result and planning corrections for practice. Every day I work to get better. It is a constant study to learn how my brain and body work together, where they falter and how to help them (me) do better.

In addition to this I work to participate in, organize and improve things in a self-governing community, and work to improve communication and caring in a marriage that has had some difficulties, not to mention interesting friendships with some people and dogs. You can see there are a lot of potential stressors here.

What I find is that my musical mind is a good stress monitor! When stress is low, my internal musical process is clear and flowing. When stressors are high the musical focus is interrupted, sometimes so much that I can't play.

Another aspect of my musical practice is that it works best when I push just a little bit on the next learning passage, then relax and do something else. When I use it right my brain learns easily.

One other issue in today's world is the Internet. Facebook and YouTube are rabbit holes which I struggle to use intelligently. Places like Mayo Connect are wonderful world expanders when used well.

My brain may be a bit slower, but my understanding of how to manage, use and enjoy it are much better than when I was younger. I feel very fortunate.