This is true. I'm now 62, but doctor tells me I have the bloodwork and metabolism of a 12-year old. Well, I apparently have the common sense of a 12-year old, too. Clearing a 40-foot x 10-foot side of the house of bricks, weeds, vines and cutting up and tossing a bunch of old trimwork from remodeled house yesterday. It was maybe 100 degrees at the time. Had a sleeveless T shirt, shorts and a hat with a brim. Next thing I know, I'm sitting on my butt with blurred vision and dizzy. Clothes were drenched. Wife brought me a glass of water, which became three. Went inside for about 30 minutes and drank another glass of water before going back to tackle the job. Didn't bother me again. But I know better and I know to hydrate before working in those conditions.
Might have been more careful if the doctor would have told me I had the bloodwork of an 92-year old. I would have been smart and paid someone else to do it.