Right?!
I grew up on a farm and I worked at neighboring farms as a teen. I also cycled everywhere, ran laps around my property, and lifted heavy. I was a machine and ate just about everything in sight.
Nowadays, I am not too bad off that I can't lift, do healthy amounts of cardio, and such. I am just finding that I am running out of gas and between my doc and all the tools that are available these days, I am finding that I am eating only a fraction of what my activities demand. Makes sense now but it's weird to be distressed by this discovery - that I am not eating enough.