You can "get your running on" at this area mini-chain where the sneakers and work-out gear are "legit" and the "expert" staff is "sincere" in "working with you" to find the "right shoe for your foot"; each branch organizes weekly group runs, and while it's on the "expensive" side, at least the wide selection guarantees you can generally "find what you need."
More than 250 styles of running and walking shoes is what sets this runner-run shop apart. If you can name the brand, they carry it, along with running tights, socks, shorts, T-shirts, and jackets. This is also the home of the Philadelphia Running Club and a good place to find out about training with a group.