Calisthenics. There's nothing fancy about a calisthenics workout, but just because it's basic doesn't mean it's not effective. A 2017 study in Isokinetics and Exercise Science put a group of untrained individuals through a calisthenics program to test the effectiveness of an exercise method that uses no equipment. Participants did a brief workout consisting of four or five exercises three days a week for eight weeks. At the end of the trial, all participants had significant improvements in posture, strength and body composition.
^ Colbert LH, Visser M, Simonsick EM, Tracy RP, Newman AB, Kritchevsky SB, Pahor M, Taaffe DR, Brach J, Rubin S, Harris TB (July 2004). "Physical activity, exercise, and inflammatory markers in older adults: findings from the Health, Aging and Body Composition Study". Journal of the American Geriatrics Society. 52 (7): 1098–104. doi:10.1111/j.1532-5415.2004.52307.x. PMID 15209647.
These types include cardiorespiratory endurance, which is how long or fast a person can perform an activity and how this impacts heart rate and oxygen consumption. Muscular strength, which is how much weight can be moved in relation to repetitions and muscular power, which is how much force can be generated during a given activity. There is also flexibility, how far a muscle group can be stretched or joint can be moved. Balance how long a particular position can be held with or without some type of activity being performed. Speed, how quickly an individual can move from one point to another. And body composition, the amount of fat on the body versus other tissues such as muscle, bones and skin.

People who are physically fit are also healthier, are able to maintain their most optimum weight, and are also not prone to cardiac and other health problems. In order to maintain a relaxed state of mind, a person should be physically active. A person who is fit both physically and mentally is strong enough to face the ups and downs of life, and is not affected by drastic changes if they take place.