During their lifetime, most people are affected by some form of ill-health or disease. Complex interplay between a number of factors affects the occurrence of disease. General factors include increasing age, hereditary factors, gender, social factors and lifestyle, working environment, psychosocial environment and outer environment. From the individual's perspective, ill-health can both be created by and can bring about a vast number of circumstances both measurable and immeasurable. The measurable effects include physical impairment, disability, sick-leave, premature retirement and death.