I was in a course last week and the speaker stated that a sales manager is not able to motivate. Motivation comes from within and you cannot change that. If it exists, you can feed it (i.e. motivated by recognition, provide recognition), but not create it.
It is an interesting thought, and upon reflection, seems true. Someone can get me to do something, but it is my own internal drive and goals that pushes me to get things done.
The speaker followed up with the statement that a sales manager can only de-motivate. The two easiest ways to demotivate a sales rep:
1. Pile on a good rep. Give them too high a quota or too much work.
2. Tolerating the low performer. A proven way to demotivate the entire team.