Push-ups and pilates are just a few examples of exercise that P rue Leith describes as “variations of hell.” Now 85, the forthright grande dame of cookery , declares: “I find exercise for the sake of exercise painful and unbelievably boring. “Being tortured on a Pilates reformer machine, forcing oneself out into the rain to go running or doing push-ups on the bedroom floor are all variations of hell for me. Ditto yoga, steps, spinning and the rest.” Married to retired clothes designer John