Five exercises, eleven minutes, no equipment at all. Devised in 1961 for aircrew posted somewhere without a gym, and still one of the most efficient routines ever written: two minutes loosening up, three minutes of floor work, then six minutes on the spot. The original ran to six charts of increasing difficulty. This is the shape of the session. Do as many repetitions as you can manage inside each window, and add more as they start to feel easy. You need: enough floor space to lie down. Apple Health logs it as functional strength training.