This article presents a process of collective formation of a new concept of mobility between home care workers and their elderly clients, who are at risk of losing physical mobility and functional capacity. A new tool called mobility agreement was introduced to facilitate the inclusion of regular mobility exercises in home care visits and in the daily lives of the clients. Our analysis starts with an overview of those visits in 2008 and 2009. We then analyze in detail one visit conducted in 2011, after two years of implementation of the mobility agreement. The analysis brings together the dialectical principle of ascending from the abstract to the concrete with the help of a germ cell, and key ideas from embodied and enactive cognition. During the visits a new concept of mobility began to emerge in the simple movement of standing up from the chair. This new concept transcends and overcomes the contradiction between safety and autonomy. Also it embeds and integrates mobility into necessary everyday actions of the old person. It is accomplished jointly with the nurse and relying on often innovative uses of everyday household artifacts. Finally, the new concept frames physical mobility in terms of sustainability. (Contains 3 figures and 9 tables.)