Programmers enjoy the challenge of writing code. Solving problems. Making things work. It's a puzzle, and damn it, come hell or high water, we're going to solve that puzzle.
No, for the most part, programmers don't get tired. In fact, sometimes we look up and it's waaaaayyyy past bedtime and yet we want to press on.
Programming is a very mental task. A coder will get into 'the zone' where his mind is solving problems just faster than his fingers can type them, and will stay that way for hours.
Yes, we misspell things. The compiler catches it.