Paul Kolb

Tough question. People are motivated intrinsically (internal rewards) and extrinsically (external rewards). What motivates a person varies widely from one to another. Extrinsic rewards can be outwardly applied by others, such as the student not earning credit if they do not participate. Those rewards are easy to enforce, as they are usually built into the grading platforms. By politely reminding their student their participation is required for credit and letting them know you want them to succeed makes them feel you are partnered with them in their goal to be successful. If they feel you are an ally, they should not feel conflicted. 

Intrinsic motivation is tricky. If the student is not internally motivated, and instructor can have the ability to inspire them. Some students are already internally motivated and there is little to no effort required on behalf of the instructor. Others, not so much. Unless the student tells you their "why", instructors can have a difficult time working to inspire them. Why did they select their program of study? That can help, but they may not be excited about the class. Searching for ways to tap into the student's "why" and bridge the gap to help them get inspired about the course is one way. Show them how the course content and learning it is in their best interest and find ways to get them excited about it.  Here is a Ted Talk that might help: https://www.ted.com/talks/simon_sinek_how_great_leaders_inspire_action/c?language=en