It is disappointing to be looked over when your company is looking to fill a management position. It is even worse when a co-worker with less experience than you gets promoted.
You hate your lazy, good-for-nothing co-worker. Your boss is considering your lazy, good-for-nothing coworker for promotion. Knowing what to do, what not to do, and how to behave will help you keep your job and your sanity.
Managers hire people to fix problems, not complain about them. Employees who are prepared to offer possible solutions are considered highly valuable. These problem-solvers are the ones who keep their jobs in a tight economy. They're also the workers who are offered merit raises, and, eventually, promoted.