How can passengers or crew members (flight attendants) survive long haul flights?

How about as a pilot? I flew the 747, some passenger flights, but primarily cargo.
During the cargo flights, I would get up every 90 minutes, go to the back of the hump, and exercise.
I’d put a blanket on the floor and do 25 sit-ups, 25 push-ups, 25 squats, and bend over touching my toes. I also carried an exercise rubber band with handles so I could work my arms and shoulders.
Copilots half my age never exercised in the airplane, couldn’t even touch their toes, and were amazed that I could.

Source: Quora