The World Health Organization (WHO) Regional Office for Europe provides recommendations on health-strengthening physical activity for children and adults, while emphasising the scientifically proven benefit of physical activity for our health. It's announced that at least 30 minutes of moderate-intensity physical activity 5 days a week reduces adults' risk of these chronic non-communicable diseases (cardiovascular disease, type 2 diabetes, colon cancer, breast cancer). Physical inactivity is thought to be one of the main causes of the obesity epidemic. Scientists have proven that physical inactivity increases the risk of a stroke by 60%, heart disease by 45% and arterial hypertension by 30%. The effect of physical exertion on our body is positive, because the respiratory and cardiovascular systems work better, non-specific immunity strengthens, the will is tempered and stress hormones decrease. It's especially important to exercise during leisure time, because the population's physical activity remains insufficient for many years. In 2012 only 31% of men and 27% of women exercised about four days a week. It should be noted that since 1994 the proportion of the population walking to and from work (for at least 30 minutes) has fallen from 29% to 18% (men) and from 27% to 23% (women). Walking to and from work is one of the simplest forms of physical activity. It's recommended to walk 3 kilometres at a brisk pace daily, or to replace walking with physical activity (at least 30 minutes). You can find out the health benefits of physical activity (endurance, strength, flexibility) using a scientifically based and very elementary table that analyses and rates various physical activities and durations in points (per week). It's an excellent result if you scored more than 25 points a week; 20–25 (very good), 15–19 (good), 10–14 (satisfactory), 5–9 (you exercise too little), less than 5 (you exercise insufficiently). Running and swimming for 30 minutes are rated at 5 points, skating and skiing (1 hour) at 4 points, cycling (30 minutes) and sports games at 3 points, gardening and walking at 2 points. Endurance, strength and flexibility are developed most by swimming – 12 points, football – 11 points, cycling, jogging and gardening – 9 points, dancing and gymnastics – 8 points, climbing stairs – 6 points, housework – 5 points, brisk walking – 4 points.