Flexibility has a double but related meaning. Flexibility is the freedom to move the body in any direction. It is also the freedom to respond in many different ways to situations. Personal flexibility is founded on both autonomic flexibility, and musclo-skeletal condition, which underpin ego flexibility. There is a functional identity between the flexibility of the body and flexibility of the person. That is, in loosening the body, by and large, one loosens the character.
There is concern even in the larger bodywork tradition, that, if exercises are pursued mechanically without insight into character, it is possible to become flexible physically but not emotionally or interpersonally. But bodily flexibility, while valuable for athletics, is not mere athleticism. Bodily health and emotional health are never too far apart. It is possible without flexibility, by heavy practice, to learn to execute physical maneuvers in dance or sports that are legitimately called skilled. But these movements are not spontaneous and are not in the service of pleasure (though they may gratify the ego). It is unconscious, unmanaged movement that is the key.
And of course flexibility is different than instability. In order to avoid instability, many people distort their stance and posture in a way that limits flexibility greatly. Often tight muscles and locked joints are involved. This is a large basis of clumsiness which derives from fear of falling. Fear of falling is enormous in our culture. It reflects, albeit at times in an exaggerated degree, a constant very real possibility because few of us are neuro-muscularly prepared for the 'balancing act' that is standing or the 'controlled fall' that is walking. Ironically, loosening up usually increases stability but this requires both faith and bodily change to be experienced where fear of falling is present.
Behaviorally, it is important not to confuse submission and tolerance for flexibility. Accommodation is setting aside one's interests completely in favor of the interests of another. This may make sense for instance with temporary house guests. It may be realistic if the other is powerful. It may be convenient if the matter is small and temporary. But as a way of life, accommodation is deleterious. Flexibility means the ability to protest and resist where that is best for the person, or those he or she represents. Flexibility implies freedom of response. In accommodation there is no freedom because the self has been negated. Flexibility allows for collaboration, which is the hashing out of mutually satisfying agreements with others.