Generated and tinkered by the greeks, the term polymath emerged. It is used today to define "a person of wide-ranging knowledge and learning." But polymath sounds more geometry term than anything else. You may be familiar with a synonym, renaissance man. Think Benjamin Franklin, or Indiana Jones.
The renaissance man is a master of many trades and skills, and he pursues knowledge for the sake of knowledge.
I think it's a lofty goal to fall into the grave with as many skills and experiences under your belt as possible. But let's not measure ourselves to founders of democracy and fictional ancient artifact finding Nazi fighters.
Start small. Brush the dust off your golf clubs, take a cooking class, download a language app. Read a book. Start a blog...