From Wilder, Wealthy, and Wise…
“Humanity’s most complicated machines can’t even come close to the versatility that is a human: if your car were able to fuel itself like a person, you’d be able to feed it gasoline or junk mail or plastic bags and it would turn that into a trip to Cleveland leaving only carbon dioxide and water vapor exhaust gas, and some form of car-poop that you presumably would compost so you could grow more car food. Oh, and the car would self-repair for decades – your tires would grow back in the middle of the night. Unfortunately your car would try to pick up on other cars, and might identify as a truck, but that’s a longer story.
The human body is excellently designed, and very, very consistent in its response to inputs. But the owner’s manual sucks, and many times we don’t operate it properly or fuel it very well. Case in point – achieving excellent health requires measurement. Of what? Unless you’re an adolescent reading this, you’re not getting taller. What parameter might be changing that you could measure, say, every day? Besides armpit hair length. That’s too obvious, and everyone does that, anyway. Think harder.
Oh, yes! Weight!”
Source: Maps, the Secret of Weight Loss, and the Source of Coke Syrup – Wilder, Wealthy, and Wise