Justin Hartley knows why Tracker is such a hit for CBS - and most of it has to do with Colter's masculinity. Hartley, 48, was asked about the show's success during a recent interview with Men's Journal, to which he said, "One of the things I really love about Colter and the way we've built him is that he doesn't apologize for his masculinity. I think that's what people are looking for.