Not just get out more, but get a rifle and target practice and hunt. Nothing tightly focuses the eyes at a distance better than shooting. More gun training growing up means less myopia both physically and politically.
I agree that for the eyes, like most of the body, use promotes fitness.
I recall my eye doctor telling me when I was prescribed glasses for astigmatism to not wear them too much, as it would make my eyes worse and more dependent on the glasses.