I think it is possible for a manager to motivate an employee because an employee might look up to the manager and strive to work harder and achieve what the manager has in his or her job. The employee might someday want to achieve what their manager has successfully feel as though they are fulfilling their desire to better themselves while they push themselves to do the best they possibly can with their jobs. The employee may love the job they have and be intrinsically motivated because they simply enjoy what they do. The employee needs to feel like he or she is an important part of the company as well, and likes to get praised by the boss, and feel needed and important. On the other hand, managers can extrinsically motivate employees by offering them better or more flexible work hours, better medical benefits, better pay, more time off. They can also allow the employee to give their input on what needs to be done in improving the company they work for. The employee may also feel that if they do not do well at their job that they may be replaced, offered lower pay and less or worse hours, and have no real shot at advancement in the future. By trying harder, even though an employee may not like the job as much as they could, this can prevent them from losing their jobs, and also keep the manager happy at the same time.
A personal experience with extrinsic motivation is when I worked at McDonalds, when I was really young. Though, I totally despised my job, I came to work on time, was polite to my customers, and did the best I could possibly do at work so I could keep my job. I needed the money and wanted to please my boss, in order to continue being employed there. I think a lot of people may have a job in which they are not completely content with and strive to do their best because they need the benefits it has to offer, and need the money badly.