Sharks don’t really pee. It gets stored it in their body tissue instead. Part of the preperation of shark is essentially pressing it for weeks to bring out the ammonia and let it break down into something that won’t kill you. Doesn’t taste good, but won’t kill you.
But presumably you don’t just stare at the wall. “Humans need something to do” is mainly bound to not just sitting around twiddling your thumbs. It’s the reason we get bored, the brain is annoyed at not having anything to focus on.
It doesn’t have to be literal work, just something you find engaging, be it going for a run, tending to houseplants, or completing your entire video game backlog.
And of course there is variation between humans. Some people cope well with having little to do, others always need to do something they find productive.