Although the Alexander Technique is about changing habits, we have to recognise that habits themselves are still incredibly useful. It's really a matter of having choice over our habits, adopting and keeping those that are beneficial, and minimising those that are less helpful. I say minimise rather than discard as we have to be realistic and not overly ideological, you don't want to end up in a judgmental fight with yourself as old habits make themselves known occasionally.
One of the problems with habituated misuse of yourself is that it leads to what F.M.Alexander called Debauched Kinaesthesia, a wonderfully Edwardian turn of phrase, or Faulty Sensory Appreciation, as it's more commonly called in the Technique. This simply states that as you filter everything through your current habits, you may not be doing what you think you're doing. This in itself can make changing habits a tricky business.As will the fact that our unhelpful habits, being the familiar, encourage a Stockholm Syndrome type relationship with them!