The fact is that we are not able to motivate others. I cannot motivate you to get to the gym, or apply yourself academically or proactively work towards a goal that has been on the horizon for far too long.
What I CAN do is inspire you. I can inspire you to create specific goals that are observable, measurable and repeatable. I can inspire you to get the most out of your education. I can inspire you to challenge yourself mentally, physically and emotionally. But, I can only foster an environment of inspiration if I am able to successfully create an environment that allows students (or anyone) the opportunity to be engaged.
There in lies the boundary of my influence. And it's scary. We all want to be able to instill success into the people we work with...at least I hope you do. But the reality is that we can only create this environment that allows individuals the opportunity to be inspired. To feel safe enough that they stretch the limit of their comfort zone. This is where growth takes place.
When people in the workplace are not performing to the levels of your expectations, instead of looking for quick fix, temporary solutions on how to "motivate" them, perhaps take a step back and evaluate the environment that you have created. Do your students/co-workers/employees have the opportunity be in engaged in their work? Make the conscious decision to give them this opportunity and see what happens.