Being able to perform physically at a level which ensures a satisfying and independent life is taken for granted in youth, but it comes under threat as physical capabilities deteriorate with advancing age. An independent lifestyle requires muscle strength, muscle power, cardiorespiratory endurance, as well as balance and motivation. It used to be assumed that deterioration in these capabilities with the passage of time in later life was inevitable. Now it is clear that much of the deterioration is due to reduced levels of physical activity. This means that it can be reversed. If physical activity increases so do physical capabilities, even in extreme old age.