Exercise and fitness are not the same thing. Fitness is a continuum, and it is activity specific. There is no such thing as ideal fitness because what it necessary for one activity can be detrimental to another. In addition, fitness must fit in to the individual's lifestyle. If fitness is not made a regular part of the lifestyle, what ever it is the individual is doing is sporatic exercise.
Fitness requires maintence.
And finally, fitness is also a continuum in that different people have different goals. In order to benefit from fitness in terms of health, it is not necessary to have extremely low bodyfat levels, the aerobic capacity to run a marathon, the strength to compete at an olympic weightlifting competition, or the flexibility to put your feet behind your neck. There's nothing wrong with making any of those things a goal, but that would be a different goal than deriving health benefits from regular exercise. In order to truly benefit from fitness, fitness needs to be a lifetime commitment. That means, you will be exercising day in and day out for the rest of your life.