How do we survive our youth? 
40 years ago I was working on my first job, so I had a little money. A local grocery store had an outrageous sale - 8 packs of Pepsi (an entire gallon, or ~3.8 liters) for 89 cents. Yes, almost for free: US $0.89.
I literally “backed up the truck,” and bought 24. I was “rich.” 192 bottles…
On my dad’s farm, there was some steep, hilly ground where I was cutting trees one day. This is seriously tough work (just moving around on the slope is hard). Wielding a chain saw, fighting grape vines and weeds, pulling branches out of the tangle around a felled main trunk…
A steamy warm day in late spring or early summer - I got thirsty. Had a trusty 8 pack with me, and I drank 5 bottles fast, probably only took 4 or 5 minutes. Keyword ‘Guzzle.’ Now I figure that is a 280 gram hit of sugar. Ouch. Almost 10 ounces - over half a pound! 
I did feel a little dizzy after that. Surely, on an empty stomach, that was one hellacious insulin spike followed by a crash. I figured it was all that sugar that made me feel that way. Kept on working and eventually felt better.
I shudder to think… The human organism is a tough one. After that, it took me 40 years to become diabetic.
We can’t go back in time, of course - we can only fo forward (or not). I do wish that way back when, I’d known at least some of what I know now.