In Alexander, we prefer to think of good use in terms of poise rather than posture, which seems to emphasise something rather fixed and static. Nonetheless, it's certainly true that we all recognise examples of both good and bad posture when we see them. Aside from being unattractive to look at, poor posture may be associated with all manner of aches and pains and health troubles, as well as reflecting issues such as low self-esteem and lack of confidence - symptoms which very often disappear when the underlying causes of postural imbalance are taken away.
During lessons, we learn to stop imposing these unnecessary strains and pressures on ourselves, and instead cultivate an even distribution of muscle tone where no one part of the body is overworking at the expense of any other, unduly tightening up in some places and collapsing in others. When things are working well there is no feeling of the need to exercise to keep ourselves in shape - the subtle ongoing movement that takes place when the body is unfixed has an energising and sustaining effect in itself. For this same reason, the feeling of needing to relax is also unnecessary, as the whole body is involved in what we are doing, and the requisite levels of tension required to provide support feel quite natural.
Sir Charles Sherrington,
"Alexander has done a service to the subject by insistently treating each act as involving the whole integrated individual, the whole psycho-physical man. To take a step is an affair not of this or that limb solely, but of the total neuromuscular activity of the moment - not least of the head and neck."