This article describes users' responses to human-like characteristics of two health promotion IVR systems. We conducted a qualitative evaluation of two systems that promoted physical activity and healthy dietary behavior respectively. Two themes that emerged dealt with favorable responses of the users to the machine's intrinsic qualities of being insentient and non-judgmental, and the users' precarious sensitivity to certain human-like characteristics of the systems, namely, the content of the scripts and the recorded human voice. The article suggests that design factors that are intended to enhance human-like characteristics of these applications elicit both positive and negative responses. Thus, even though many users enjoyed and appreciated the human-like performance of the machine, some who were more sensitive about their exercise or dietary behavior preferred a non-affective response by these systems, i.e. they preferred the system to behave like a 'machine' (without emotions) rather than a 'person'.