I joined a running club for this purpose. There are clubs all over the city, some more chill than others. I've found it's a great way to meet new people, make friends, explore the city on foot, and exercise! Philly Runner has a great list: https://philadelphiarunner.com/running-groups-in-philly

Edit: in case you're not a runner or are unfamiliar with the idea of a running club, don't be scared off thinking it's some crazy hardcore thing. Plenty of groups (incl the one I run with, Passyunk Beer & Java Runners) are full of just regular people, many who run slowly but enjoy doing so with others.