As a Crossfit Coach I have a cut and dry attitude about what can be considered fitness.
Fitness is measurable. Anyone who tries to argue otherwise is either ignorant or has something to gain by telling you otherwise. Fitness is being good at all ten General Physical Skills (see previous page). A persons ability to move heavy things far and fast relates directly to their fitness level. Fitness can be measured simply by determining your ability to do work.
Workouts need to be constantly varied, high intensity and using functional movements.
Constantly varied to mimic life and reduce plateau, high intensity to produce the best response (metabolically) and functional movements because they produce the highest power output.
If you are able to achieve a high work capacity (fitness) and maintain throughout your life then your quality of life is greatly improved in turn.
For a more in depth discussion check out the following links:
What is Fitness?
Understanding Crossfit
