Intellectual vitality and physical vitality are intertwined
I agree that curiosity is fundamental, and the need to keep shipping — get that right foot following the first foot every morning!
Being nearly 72 I share your Dad’s observation, and I’d add another. Many people around me, down at the local shopping centre, for example, have not just lost their intellectual curiosity, they’ve lost their physicality along with it.
it is not just that physical activity stimulates biological benefits for the brian e.g. cleans out the wastes, brings new nutrients, enables neurogenesis, balances neurotransmitters, but that it adds our capability to face the world squarely in the eye.
There’s no need to be stooped at my age. There’s every reason to expect that you can still run and play soccer with your grandkids.
Keep moving, keep building your muscle mass and strength, keep up the flexibility exercises, and try going for a run. That all helps power your curiosity.
I know it has for me.