Aurora Borealis

 A panel here looks at the Canadarm.

The human body starts to have issues with extended tours in space, and if you're up there for months on end, there are ways to counteract things like muscle loss- exercise. Using customized exercise equipment on the ISS, astronauts must exercise two hours a day to counter the effects of being up there. It makes recovery upon returning home go smoother.

They're also busy with research- scientific experiments, checking on each other's physiological state, for instance.

And part of their free time inevitably includes time in the Cupola, which gives a view back onto the Earth.

A reproduction of the Cupola is here, with footage from the ISS flashing by. When I entered, aurora borealis was shimmering.