It is clear that it can work for physical reasons, as S. exercise
actually eliminates some of the problems. It make easier to breath for
one, improving oxigination level as result. Already a good reason for
better mood. By prolonged practice it widens the large bronchi, those
making the improvement permanent.
Besides, brain is a physical organ itself. It just does
not work very well if say not enough nutrients are coming in, or blood
has reduced oxigen level, not to mention levels of different hormones,
that also can be altered by physical activity. So making body work
better improves work of the brain and so improves the outcome of
thinking process. Maybe mood improves because some of the issues
_actually_ find a resolution!

As for purely psychological, it is more complex. But I can see one
mechanism, similar to meditation - it allows to break up the infinite
loop of thoughts that don't converge to a desirable resolution. By
"resetting" the brain, it allows to start thinking process from new
set of "seeds" and this way it might come to completely different
solutions.
But meditation requires a lot of training to get it right, while
exercise allows to accomplish the "reset" equally well for a novice or
experienced practitioner.

Regards,
Evgenij


--- In strelnikova_exercise@yahoogroups.com, mclaym1@... wrote:
>
> I believe depression occurs for two reasons. The first one being
purely
> psychological. A person tries to do something. Things do not work
out. Depression
> sets in.
>
> The second reason is physical. May be, there is some chemical
imbalance in
> one's head. Some people are just predisposed to being depressed much
like some
> people are predisposed to having certain conditions.
>
> I believe in both cases, these breathing exercises can help. Yes, it
is a
> simple explanation, but it makes sense.
>
> We live in a society of "easy solutions." It is much easier to take
a pill
> than to do anything else.