Introverts (like myself) enjoy many of the same things as extroverts; they just find being around many people to be wearying. This does not mean that they are necessarily shy or lack empathy or don't like people; it's just more "work" to be part of a group..
So, introverts balance social activities with alone time. Solitary activities like reading are stereotypical introvert pastimes. And introverts might prefer sports like hiking or wall-climbing or running that can be performed solo to those which must necessarily be played as a group, or prefer interacting with people online instead of face-to-face. But introverts also join sports teams, and attend concerts and conferences, and go on dates or visit friends. They just mix the fun things that are "effort" (because they involve other people) with relaxation that doesn't involve other people.