You don’t have to take part in strenuous sports to get problems; not everyone that has tennis elbow is a tennis player!
Normally your body should be reasonably well balanced. Your muscles should just be working hard enough to support your weight and you should have enough flexibility to be able to properly dissipate all the everyday stresses and strains.
This is all controlled subconsciously by your nervous system by a process called motor control.
However muscles and joints may be injured by traumas such as falls, bumps or car crashes, which cause altered motor control and changes in movement, so muscles, joints or ligaments can be overloaded leading to aches & pains within these tissues.