Asanas on the other hand, are different as far as taking the position (slow and controlled movements), maintaining the position (steadiness, comfort & relaxation) and releasing the position are concerned. The asanas (physical positions) can be mastered progressively through following four levels.
If one practices Asana with
these four levels in progression then one is said to have mastered
the Asana, which results in perfection on physical and mental
aspects. Ideally if one can maintain an Asana for three hours
without discomfort, it is mastery on physical level, if one can
focus the mind on one object during this practice then it is
mastery on mental level.
The natural condition of the
body and mind is a relaxed state. By regular practice of Asana this
relaxed condition is achieved without efforts. So if you are just
sitting in the office chair, try and make your body relaxed and let
the mind become calm & peaceful. Then there will not be any
stress or strain on physical level and no thoughts in the mind. Now
we can easily understand what an asana is.
The similar description of Asana
is found in Hatha Yoga Pradipika which says that "One can achieve
sound health, stability, lightness of body and mind with
Asana".
In GherandSamhita (Another text
on Hatha Yoga), the author describes the effect of asana as "The
result of Asana is perfecting the stability of body and
mind."
We can see the other effects of
asana in day to day life such as increased efficiency, stamina,
increased immune capacity, quiet and calm mind, easy control over
emotions and improvement in attitude.