1. Read non-fiction. All non-fiction. Everything. If time becomes an issue read summaries of everything. But good summaries...they can be hard to find, but they are there.
2. Realize how broad an undertaking that is. So figure out the major components of human undertakings and make certain you cover all the components. Say agriculture horticulture and food, building, clothing/fabrics, infrastructure (electricity, water, oil/gas, wastewater, transportation, communications, computing), manufacturing, mining, medicine, law and order, military studies, entertainment, visual arts, music, literature and rhetoric, linguistics, education, religion. A true university education, as in learning everything a large university has to offer at some reasonable level. Not just checking off a distributional requirement.
3. Each of these are a human endeavor and are defined by a fairly distinct subculture with vocabulary, norms, values, ways of thinking, cultural code words. Learn them. Don’t learn to be a nurse, but “grok” the nursing subculture (which will involve learning a little but don’t go poking people with needles). Don’t practice medicine, but maybe read the Merck Manual. Empathize with the subcultures...
4. Science and math is the universe (in the form of human beings) straining to understand itself. Learn the STEM subcultures, but then learn what the universe has found out about itself, at a suitably abstract level.
Once you’ve done that, then explore whatever brings you joy. Keep current, but once you have the foundations they are pretty light updates. Then go deep on whatever personally interests you. They become the spice of your personality in this human life.