What does being fit mean? From my point of view, to consider yourself fit you need to have a solid foundation in the main components of fitness: muscle strength, cardiovascular endurance and flexibility. Otherwise, you are only as fit as your weakest link.
A perfect display of overall fitness would be crossing an obstacle course or, to the extreme, finishing an "IRONMAN" competition. These grueling events, although very different from each other, require the competitor to dominate different areas of fitness.
Training for overall fitness requires you to work on the components of fitness in a specific manner and in a combined effort, recruiting them altogether as you would in a "functional" type of work out.
Incorporating overall workouts into your training regimen is an excellent way to achieve new heights in fitness. These workouts, although not necessarily pure muscle isolation, have crossover benefits and you will see an increase in strength, along with a higher cardiovascular threshold. Although having a rock hard body is not an idea to reject, we also need to work on the other qualities that really make us fit.
"when we talk about being fit, we should use overall fitness as the guideline to determine one's true level of fitness".
Since what measure our true fitness are our performance capabilities, let us be fit and not just look fit!