Initiatives in medical practice that are said to re-insert the subject, thereby overcoming the problems of objectifying practices in earlier times, often operate with a notion of bodies and selves as pre-established entities. In this paper, I will try to show some of the work it takes to produce or perform self-monitoring subjects who participate in keeping their asthmatic bodies in control through the use of an online control center. I argue that the bodies in control and the competent selves related to this technology depend on the establishment of a chronically ill body and on the decentering and incorporation of the clinic in everyday life. Passages into the body are to be kept open in real-time through the involvement of materially heterogeneous arrangements.The distributed character of this work creates and is dependent on an ambiguity in relation to the question of agency. Who or what acts, decides, looks, knows and so on,is not necessarily defined or otherwise clear in the day-to-day use of the technology.Instead, agency becomes performed in particular instances, where it might become the property of one part of the network or another. Creating the asthmatic as a free,autonomous agent in this instance depends on blurring other nodes in the network in the day-to-day use of this technology, these being, the physician, the technology, and the scientific set-up. As such, I argue that agency in the form of the self-monitoring competent ill, is best understood as a successful performance of invisible passages and links that hook up bodies,other selves, science and medical practices.