As an older traveller, I remember the days when suitcases didn't have wheels and when trolleys weren't a thing at airports. Travelling in the 50s/60s, you carried your stuff. Even though my checked suitcases have wheels, and I'm much older, I always make sure I can lift every bag. (Particularly necessary in Hong Kong when the taxi drivers can be a decade or two older than me.) Of course it helps that the carry-on allowance in these parts is usually 7-8 kgs!