It is very possible for a manager to motivate an employee. There are different ways to motivate an employee, intrinsic motivation and extrinsic motivation. Intrinsic motivation is when motivation is provided by an activity itself, something that makes it fun. Extrinsic motivation is motivation that comes from consequences of activities like getting rewarded for doing well or being good.
A way for a manager to motivate an employee using intrinsic motivation is to make work more fun for the employee that the manager is trying to motivate. There are ways to make anything fun, just have to find out what that would be for the place that the employee is at and for what that employee does every day. People like to do stuff that is fun and this way it would not feel like work as much, it would make the employee want to come to work and the happier the employee is with their job the most likely they will be motivated to do well at it.
A way for a manager to motivate an employee using extrinsic motivation is to offer rewards for doing well. Everyone young or old likes to get rewards for doing well or working hard. It makes if all feel more worth it. It does not matter if it is something small or something big. It could be anywhere from a compliment like saying good job or you are doing great to a party for meeting the quota or for being the best employee for that month. Some managers give out plaques to the employees that did best for that month and hang it on the wall for everyone to see. No matter what the reward is it will make the employee be motivated to do it again and to even do it better the next time.
Psychology: An Introduction, Twelfth Edition, by Charles G. Morris and Albert A. Maisto. Published by Prentice-Hall. Copyright 2005 by Pearson Education, Inc. Chapter 9