Health can be defined as 'complete physical, mental and social wellbeing and not only the absence of illness or infirmity'. This is an interesting definition as people tend to feel they are healthy simply when they do not feel ill. This definition clearly describes that health is much more and involves feelings of happiness, social interaction and energy.

Fitness can be defined as 'the ability to meet the demands of the environment' and relates to how physically demanding life is. Therefore, a person doing an office job requires lower levels of physical fitness than an Olympic athlete. With so many people working in non-physical or sedentary jobs this means that the fitness requirements of society decrease, leading to a heavier and less mobile society. In this negative context, health levels tend to decrease and people take part in much less exercise.

Exercise can be defined as 'a form of physical exercise done to improve health or fitness or both'. It is recommended that adults and children follow different activity routines in order to maintain good health and fitness:

Children and young people - seven sessions of sixty minutes per week. At least two of these sessions should be of high intensity exercise such as running, jumping or cardiovascular based sports. The seven hours may be spread out over the course of a week.

If a person does not take part in regular physical activity, exercise or sport then they are at risk of a number of illnesses and negative effects such as: