An active body prevent degeneration of the brain and effect your emotions.
Depression is a state of mind involving different organisms in the brain,
like the amygdala,(fear & aggression) and the hypocampus (memory).

They are in  turn connected with the brain cortex. The different parts of
the brain communicate with each other by means of electrical waves and
neuro-transmitters, chemical substances.Those combinations determine
what you can do, what you feel and what you think.

Anti-depressants intervene with neuro-transmitters, like serotonine.
Serotonine influence your mood, self confidence and appetite.
A deficiency of these neuro-transmitters could lead to feelings of depression,
but this theory is not proved.

The tendency is to ascribe depression to a combination of genetic factors,
processes which are happening in the cortex.
The upper layer, which is involved in  perceptions of the senses, movement
and reasoning, and the neuro-transmitters.

Hypogondria and lack of interest and pleasure could be signs of depression.
If these mood disturbances happens with a lack of appetite, insomnia, fatique,
lack of concentration, feeling of impotence or fear, restless, crying, worrying,
repeating thoughts of dead or suicide, etc., there is a common ground for
real depression. One out of seven people encounter feelings of depression
in their lives.

Your brain determines how you treat your environment, but the opposite is
also true: your environment forms your brain.
The good news is that we can do something about the loss of brain cells,
when we get older.Our brain has a high level of plasticity, in other words,
our brain is mouldable. It adjust itself to the demands.

The structure of your brain is determined by what you do.
They researched the brain structure of London Taxi drivers. They have to know
the complete plan of London. This effects the hypocampus of the brain,
an important part of the brain that takes care of the data input and of
spacial observation. With London taxi drivers this part of the brain appears
to be bigger than with normal London drivers. It even grows through the years.

Besides structure you can also influence communication between different
parts of the brain. According to research, different parts of the brain
before and after cognitive behaviour therapy are changed.
Apparently, you can change your emotions, behaviour and your thoughts.

Movement plays an important role. Movement produce substances that stimulate
the plasticity of the brain. How this works is unknown.
But we know that movement works protective.
Rats who move a lot, for example, have more connections between cells
in the hypocampus, the part of the brain that is enlarged with the
London taxi drivers.

We also know that movement counter act degeneration of getting older.
You keep your memory in good condition and you can plan better.
We also know that movement helps to reduce stress.
Long lasting stress damage the hypocampus.

From research we know that by practicing weight-and condition training
for half a year, the results are excellent.
This means: when you start moving now, you immediately make progress.
It doesn’t matter, whether you have been practicing sport before or not.

Movement also influence moods your brain produce.
Well known is the runner’s high with runners.
Running produce neuro-transmitters,like endorfines.Endorfines surpress pain.
Pleasant side effects are feelings of happiness, or even a feeling of euphoria.

Running is a well-known therapy for people suffering from depression.
Stiff cycling has the same effect: cycling relaxes and the fresh air also
takes part in it. The surroundings influence via our senses our state of mind.
When you cycle, they al get a change. Wind cleans our brain.