Effectively teaching an Introductory Physics for Life Science (IPLS) course means engaging life science students in a subject for which they may not have considerable preexisting interest. We have found that the inclusion of topical examples of relevance to life-science students can help to engage students whose initial interest in physics is less developed, but that different examples and models vary in their effectiveness. Examples that ground physical models in authentic biological and biochemical contexts with which the students are already familiar, and about which they may already have authentic driving questions, are especially effective. By analyzing data from (1) survey instruments assessing student attitudes and interest in particular life science examples, and (2) interviews conducted with students before and after instruction, we identify features of our IPLS course that appear to be particularly important for fostering student learning and engagement. We suggest that some of these features might also foster student interest in more traditional introductory physics courses.