I'm afraid I don't have the answer to that, either. I can tell you that the definition of physical fitness has changed with the advent of automation to refer to whether a person's body operates efficiently at work and leisure.
Fruits, veggies & protein and your body should be able to function efficiently and resist certain diseases
Im a sports man ,Physical fitness is regular stuff I do to keep fit. Oh, yeah? Generally physical fitness can be had by good nutrition, exercise and rest. What steps do I need to take to keep my body in shape? I honestly don't know, though I can tell you that fitness is the state of being fit. So what type of  food do I need to eat regularly?
However, with automation and changes in lifestyles ''physical fitness'' is now considered a measure of the body's ability to function efficiently and effectively in work and leisure activities, to be healthy, to resist hypokinetic diseases, and to meet emergency situations.