I teach in a fully online program so it's important to motivate my students early on. One thing that I find effective is to start the semester out with something personal and fun, not necessarily course related. I'll ask them to post a picture that describes them or their dream vacation destination, etc. It breaks the ice in a way where it makes the course less tense and stressful the first week rather than jumping right into the content. This simple activity seems to break the ice and motivates students to do well and participate right from the beginning.