Seentary lifestyle is a medical neologism used to denote a type of lifestyle most commonly found in modern (particularly Western) cultures. It is characterized by sitting or remaining inactive for most of the day (for example, in an office), with little or no exercise. It is believed to be a factor in obesity, and, as such, may contribute to other diseases, such as type II diabetes, heart disease, depression and even hemorrhoids. Lack of exercise causes muscle atrophy, i.e. shrinking and weakening of the muscles and accordingly increases susceptibility to physical injury. Additionally, Physical fitness is correlated with immune system function; a reduction in physical fitness is generally accompanied by a weakening of the immune system.