Yoga means, to unite.
Through yoga, many people start to see the interconnection of everything, the symbiotic interaction of flora, fauna, humans, maybe beyond.  Yoga is, “to yoke”, to realise the oneness of all. During the practice of yoga people come to realise the importance of patience, and to allow time to take its course. We learn that we can't make our joints, muscles, body, and mind to adjust to new postures, moves, routines, situations any more than we can force an acorn to grow into the mighty oak. Yoga merges together the mind, with all its murk-hidden-treasures and the body with all its restrictions and potential.
Maybe the achievement of this successful line-up it's both what leads to, and what results from, the Soul.


What is Prana?
In brief, it is the vital force in every being, the subtle energy behind and within everything that IS.  Prana is said to exist within everything from a brick to a solar system, the difference being only in the degree of manifestation.  It is Prana that causes a seed to burst into life, causes wounds to heal and the stars to move in the Heavens.  It is the basic Life-energy.  
 Our bodies contain and use Prana.  We take it in from the food we eat, (fresh, natural food) from the water we drink, from sunlight, but mainly from the air we breathe.  The fresher, the purer the air, the more Prana it contains.  This is why it is so revitalising to breathe fresh air by the sea or up a mountain.  When we breathe in, we draw in Prana from the air, but we do not breathe it back out again.  Instead it is stored in the body, in certain centres, to be used when needed.  
 Illness in yoga is thought of as a shortage of Prana, or the Prana in the system being out of balance.  Sometimes, for various reasons, there is a blockage in the system which prevents the free flowing of Prana and this causes dis-ease.  

This is a balanced breathing exercise. Take an in-breath followed by the out-breath that are the same length, but the length of each following breaths is different. 
The count goes up and down like steps. On the first breathe, breath in and out for a count of 1. On the second breath, in for a count of 2and out for 2, then 3, then 4. After you reach an In and Out breath of seven counts, (maximum) go back down, this time breath in for 7 and out for the count of 7, then 6, then 5, 4, 3, 2, 1.
All of that is repeated 3 times.

If you find it difficult to get up to 7, then just go to 6, especially on the first round.  If 7 is not enough, you can go up to 8 or even 9, but that is rather extreme, and for most people 7 will be enough.  

                                *Always take a short pause after breathing in and breathing out*