In the northern part of my country, which is very arid, people use some devices that consist of a mesh that captures morning sea mist. It condenses on the mesh and it's then collected in a drum.

I have met several old poets, mathematicians, doctors, etc. which have a very good working brain, and the common thing between them is that they keep creating, thinking about problems, learning new things, i.e. excercising their brains. Probably a good diet helps too.