The current need to adopt a healthy lifestyle opens the way for researchers to investigate the efficiency of using technology to motivate a change towards such behavior. Senior people's technology adoption barriers have been largely investigated in previous research but remain unclear to design efficient solution to promote behavior change in the long term. In this paper, we present the findings of an experiment with 20 older adults using pervasive sensors for 6 weeks at their homes. In particular, we present their attitudes for physical activities and self-monitoring technologies before and after the actual usage. We then discuss the opportunities and challenges for designing self-monitoring technologies for healthy aging.