OP is correct to be thinking about EC's in terms of what gives a person joy. Wellness is a buzzword these days, but for good reason. As physicians, we work hard, and one needs to MAKE time for other activities that bring us joy. Mostly, this is about finding ways to meaningfully interact with others, including people outside of medicine. Club sports will be one route at medical schools that are part of the bigger university . Most universities with a rugby team, water polo team, badminton team etc, are club teams and grad students get to be a part of the teams. You may miss some practices and games, but not usually a problem. And some schools have other intramural sports activities.
There will be time to shadow specialties that you might not get exposure to in medical school, like IR, radiation oncology, dermatology, ophtho, pathology, etc. There will be courses for Spanish for medical professionals at most schools or other electives such as in global health or social justice. Research is always possible, though with some of the schools where there is a compressed curriculum (1.5 yrs) for preclinical, one needs to be careful of spending too much time doing research. Students have, as one poster mentioned, run businesses in their "spare time" in medical school. Many schools have a free clinic that is a good way to get hands-on some clinical experience with the guidance of near-peers, even very early in the clinical year, and can ultimately get leadership responsibility as an upperclassman.
Residencies care little about EC's - though certainly leadership is always important to residencies, so if you develop leadership roles in your EC.s they care. Or if you teach in a role in your EC's, that is appealing bc being a resident means teaching junior residents and medical students.