I was at primary and junior school in the 70's. First port of call at 3.30 was the corner shop and the penny tray for sweets... the queue snaked out of the door...
We walked home eating our pink shrimps, chocolate spanners, spaceships etc, then we went out to play, on our bikes, kicking a football around, hide and seek, or any other games that we felt like playing until it was time to go in for tea at about 5.30pm. In summer we went back out after tea for another hour or so.
In winter we went swimming, brownies, or played indoors.. but we were moving around..
I can honestly say that out of a school of 200 pupils, I can only recall one obese child. The rest of us were whippets, despite eating "stodgy" school dinners, and sweets...
In that decade, nobody was obsessed with BMI, sugar control, salt control, and additives.. yet we have all survived, or at least the vast majority of us have, and gone on to have our own kids, and live healthy lives.