During the render process my PC is literally useless, so I go and play some games on my phone while it finishes. Or fall asleep, lol. I usually wake up within an hour though, so it's not all bad. A small nap.
Sit and watch videos usually. Or I render it when I get dinner or such so I won't really have to wait!
My uploads take long and destroy my internet so when I upload I make sure nobody's using the internet.