I'm in a new relationship. It's a love-hate situation, really. And it's with a machine. A Megaformer, to be exact, but I just call it the rack, in a whisper, the way kids say the names of monsters. Ropes, straps, pulleys, leather—part torture device, part lusty menace. This is strength training that hurts just right. It's my frenemy. My frenemy with benefits. And starting this week, I'll be cracking the whip at SLT Flatiron every Monday night. The game plan is mine, but you can pick your poison: 7:30 or 8:30. Be there.