A new Peloton-Fitbit partnership email landed in my inbox this morning, offering members $40 off a Fitbit Charge 6 for “real-time heart rate tracking, powered by Fitbit.” At first glance, it looks like your usual cross-promotion between fitness brands. But it’s really something much more strategic. Remember that Peloton-Hyatt hotel partnership I wrote about a few days ago? That was about maintaining workout continuity while traveling — keeping customers connected to their routines away from...