In general, a structured recovery plan, adequate rest, moderate-to-intense physical activity, and good diet are the keys to achieving physical fitness. 
Fitness prior to the Industrial Revolution was described as the ability to complete daily tasks without experiencing excessive fatigue or sluggishness. A state of health and wellbeing, physical fitness is more particularly the capacity to carry out daily tasks, sports, and jobs. But as lifestyles have changed due to automation, physical fitness is now seen as a gauge of a person's capacity to maintain good health, fend against hypokinetic illnesses, strengthen their immune system, and perform well in an emergency.
 

Along with the physical health benefits of fitness, it has also been shown to have a positive impact on mental health as well by assisting in treating anxiety and depression. Physical fitness can also prevent or treat many other chronic health conditions brought on by unhealthy lifestyle or aging as well and has been listed frequently as one of the most popular and advantageous self-care therapies. Working out can also help some people sleep better by building up sleeping pressure and possibly alleviate some mood disorders in certain individuals.

Recent studies have shown that the skeletal muscle's function as an endocrine organ mediates many of the advantages of physical activity. In other words, when muscles contract, a variety of chemicals called myokines are released. These compounds aid in tissue repair, new tissue formation, and anti-inflammatory properties, all of which lower the chance of acquiring inflammatory disorders. Textbooks frequently depict this as a triangle with three points, standing for mental, emotional, and physical fitness. Due to the relationship that has developed between physical attractiveness and human fitness, the worldwide fitness and fitness equipment sectors have become more active. It has been demonstrated that maintaining physical fitness helps both avoid illness and speed up recovery from injuries or illnesses. 
Individualised comprehensive fitness programmes usually concentrate on one or more targeted skills, age- or strength-related demands, such bone health. A lot of publications also stress the importance of mental, social, and emotional well-being for total fitness. Fitness is associated with those who have a considerable capacity for either anaerobic or aerobic exercise (i.e., strength or endurance). Being in a fit and healthy state is referred to as fitness. Around 1950, the word "fitness" expanded by a factor of ten in western slang, possibly in line with the Industrial Revolution and the aftermath of World War II.