In this paper, we present a user study of the heart rate monitors (HRM), which is a commonly used personal wellness technology. HRMs have been used over several years for adjusting the exercise level and in the advanced form, also for measuring the users' fitness level and its progress. The user study included interviews with the HRM users and a survey with over 860 active or former users. We identified four different types of HRM users based on the current usage activity and their perceived progress of usage motivation within time, and compared their perceptions of the strengths and weaknesses related to HRMs. The findings provide valuable information for understanding the end-user needs and background knowledge for developing personal wellness technologies and applications further.