There are various signs that are indicative that it may be time to move to a different job, or or at least pursue more rewarding opportunities at the same company. Some signs include a lack of challenging work, a loss of status, and other indications that a career change may be necessary. Workplace psychologist Dory Hollander defines job satisfaction as enjoying the culture of the workplace, being able to envision oneself at the job years down the road, and not feeling that the job is interfering unduly with one's personal life.
See "Your job: Signs you've stayed too long", Jeanne Sahadi, CNN, July 27, 2005