Examining lean and healthy habits throughout my life

I have started looking back over my life and examining times when I was naturally lean and healthy. By "naturally" I mean,  I didn't put thought into it and somehow my body normalized at a lean and healthy size.

I am not talking about the several times in my life that I punished my body into submission to get to a "skinny" weight  Most of these times I was not healthy. Just skinny. Every one of these times was a struggle to get the weight off, and then it came right back.

I am talking about when my body was naturally lean and healthy.

I can think of three times this happened.  1) when I was pregnant, 2) when I had surgery and 3) during  my childhood, until I move to college when I was 18.

I was born in the 50s. Back then times were different.  This was a few decades before the preoccupation with diet and exercise. Weight and health was not a huge issue during the 50s and 60s.  Almost everyone I knew then was lean and healthy.  I think I may have known 4 or 5 obese people throughout my whole childhood.

When I started looking at the months I was pregnant and the months recuperating from surgery, I realize that my eating and activity habits were much like my childhood.  During those times my only objective was to eat as much as possible to ensure I was getting all the nutrients I needed for a healthy body. During pregnancy I wanted a healthy baby.  During surgery recuperation I wanted to heal as quickly as possible.

It has occurred to me that I need to look more closely at my eating and activity habits during my childhood to see if I can determine just what I, and all my family and friends, were doing right - what did we do to contribute to our lean and healthy bodies and how did I get so far away from those habits?