Hi Heather:
Small breaks work well. Even simpler methods can be effective. For instance, just stop for a moment and ask a silly question like, "who were Lucy and Ricky's landlords (last name)?" Then get back to your topic.
More aggressive might be changing the way your delivering your topic. If PPT, change to overhead or white board or computer.
When you really need attention of the students, changing activities. So if lecturing, switch to class discussion or in class worsheet. Keep students busy and active.
Regards, Barry