A Definition of Physical Fitness - MISSION: Capable.
Physical fitness is measured by how well you look, feel, and perform (as Robb Wolf loves to say). Your physical fitness will be influenced by four things: Nutrition, Sleep, Stress, and Activity. Note that I didn't list exercise at all! This is because exercise is a sub-category under Activity. How well you eat, how much and well you sleep, how much stress you have, and how active you are will be what determine your level of physical fitness.