Fools and con men lay claim to knowing how to make deals. But talk, of course, is cheap. Only recently have I met the one true Master of the Art of the Deal. Perhaps he is an unlikely candidate for that title, given that he is illiterate, incontinent and does not yet know how to tie his shoes. I am talking, of course, about my brilliant grandson, Theo, who is 2 ½.

He knows his audience. He works them, plays to their strengths and weaknesses. His parents and grandparents want him to eat a full meal, justly concerned that he may become malnourished and not build enough brain cells to get a scholarship to Princeton, Yale, or Harvard.

But then he becomes cute and playful and wants to build Lincoln Log homes and demonstrate his engineering/arthitectural erudition, so the elders cave and play, sure he’s the next I. M. Pei, or Brunelleschi, or Frank Lloyd Wright.

And then later, when it’s bedtime and his father says, “I’m gonna count to five and then I’m taking you to bed,” well by “4,” the little dealmaker pulls his meal-ticket: “Poppa, I’m hungry.” And so he’s back to the kitchen to stave off starvation. He finishes the saved plate of his asparagus and chicken, and even gets Grandpa Jon to secretly give him a scoop of pistachio ice cream and cookie (don’t tell his parents).

When I told this story to a brilliant young colleague of mine who has young children, she laughed and said, “The key is that you should not negotiate with terrorists.”

Every day in my office, I try to negotiate with people to increase their exercise. Ah, but the human body, just like my brilliant colleague, does not negotiate. It’s more like hassle-free buying. And the body is a cheapskate. You don't get fit unless you pay with effort.

The body makes the gazelle hunter running on the savanna into a strong runner by making lithe, thin muscles, but it makes the stone-hauler become bulky, strong and muscled. The fact that the body can adapt demonstrates the sheer elegance of Mother Nature.

But you get what you pay for. An office worker, engineer, doctor, lawyer, nurse, waiter or waitress — each body adapts to their level of exercise. And when that exercise is nothing, then the frugal body starts to decay. Nature and evolution have no use for couch potatoes.

Still, people try their pointless negotiations: rich people go to fancy grocery stores to spend way more money on “organic,” “Paleo,” “locally sourced,” and in the same cart put out-of-season raspberries and avocados shipped from Guatemala using fossil fuels, thinking they can buy their health with whatever fad is cool. They bring excuses and say they'll exercise. But, unlike parents and grandparents, Mother Nature is a much tougher negotiator.