Over the past decade, the miniaturisation and cost reduction brought about by the semiconductor industry coupled with advances in wireless communication, sensor design, and energy storage technologies have made pervasive sensing a reality. Integrated micro-sensors no more than a few millimetres in size, with onboard processing and wireless data transfer capability are the basic components of such networks already in existence. The ultimate aim of the body sensor networks (BSN) is to provide a truly personalised monitoring platform that is pervasive, intelligent, context-aware, and invisible to the subject, thereby avoiding activity restriction or behaviour modification. Although the original aim of BSN has a strong healthcare and well-being monitoring focus, it also has important applications in sports, training and interactive gaming. With the increasing range of applications proposed for BSN, its future development is expected to change many aspects of our daily lives. The focus of this talk is to present the basic background and the latest development in BSN by addressing the technical challenges related to biosensor design, power scavenging, and low power wireless communication; examining the need for autonomic sensing including context-aware sensing, mutli-sensor fusion and data mining; and assessing the future of pervasive sensing for healthcare, general well-being and sports applications.