I hear you about having little mental energy left. There are lots of intensely dedicated teachers but it is unreasonable to expect that they will be on 24-7. They get to have families, to have hobbies, etc., just like everybody else. Just like engineers, police officers, and any other highly trained professional.
(It is especially discouraging, for me, when someone writes a letter to the editor seeming to assert that teaching is something women do so they get summers off with their kids, kind of a hobby. Those make me cringe.)