Sometimes it is underestimated how stressful the role of a manager can be. With staff needing assistance, coordinating and having your own workload to worry about, it can be hard to keep your head in these situations.
Many managers hate meetings as they can drag on and on with little getting accomplished. However, they typically have no choice in the matter, and must show their face in the meetings to give directions to their team or to get status reports on running tasks.
Many people would probably say that having a mentor would help their careers, but few people actually have one. The value of a mentor cannot be understated, just as a value of a coach for successful sports players.