Unlike many martial arts, Shintaido does not always advise the practitioner to "seek the center" or to "be centered". While a T'ai Chi practitioner might try to be always in balance and centered -- near the center region of the area representing the ability to keep balance -- a Shintaido practitioner often explores the regions where s/he is out of balance or almost out of balance. The most representative and distinguishing movements of Shintaido (ageoroshi, shoko, most kaihotai movements, eiko, shintaido jump and other jumping, many of the meditation postures...) demand that the practitioner extend and reach out beyond or almost beyond the limit of keeping balance.
When you operate near the limit of the range of balance, important muscles surrounding the spine, in the lower back, and around the pelvis -- muscles related to keeping balance -- are powerfully engaged and trained. So this can have a beneficial and therapeutic effect on the spine, the root of our ability to balance ourselves vertically in this world of gravity (which weighs on us relentlessly 24/7 from the moment we're born till the day we die). It can untangle and detoxify the distortions and maladjustments imposed on our bodies by the demands of the modern "civilized" lifestyle.
At the same time, the psychological and emotional effect of operating near the limits of balance is to encourage psychological and emotional growth. The will to challenge our limitations psychically is not really separate from the process of challenging physical limitations. So an important part of Shintaido training is overcoming fear. Shintaido practice helps to develop bravery through physical challenges that push us beyond our "comfort zone" -- yet with minimal actual physical danger (in contrast to challenging adrenaline-addictive activities such as skydiving, rock climbing, walking across beds of hot coals and so on). Rather than just physical bravery, this is a more internal bravery: the bravery to handle whatever experiences are difficult for you.