I have been able to use Team building exercises/games to remind people of just how essential each person is to the whole team. One example has been having the team members take a string and weave it from person to person as the tasks would flow. When completed they see how each person is a part of the process flow and how we are all tied together. Reminding people of their value is important to keeping them engaged. As you suggested, goals can help to keep team members on track and engaged together to accomplish them.