Fifteen-foot Himalayan pink-salt walls, infrared saunas, doggie daycare — when it comes to his massive new Flatiron District gym, celebrity fitness mogul Alex Reznik is leaving no kettlebell unturned. And after converting the storied Clay Health Club + Spa at 25 W. 14th St. into the extravagant members-only Complete, the self-described “turnaround guy” is bringing...
