Physical inactivity has reached epidemic levels in developed countries and is being recognized as a serious public health problem. Recent evidence shows a high percentages of individuals worldwide who are physically inactive, i.e. do not achieve the WHO's present recommendation of 150 minutes of moderate to vigorous intensity per week in addition to usual activities. Living in sedentary lifestyle is one of the leading causes of deaths and a high risk factor for several chronic diseases, like cancer, cardiovascular disease, diabetes type 2, and osteoporosis. This article summarizes evidence for relative risk of the civilization diseases attributable to physical inactivity and the most important conclusions available from the recent investigations computing the economic costs specific to physical inactivity. The findings provide health and economic arguments needed for people to understand the meaning of a sedentary lifestyle. This may be also useful for public health policy in the creation of programmes for prevention of physical inactivity.