By breathing we are supplying our body with oxygen. Oxygen we need to do things physically like e.g. arm or leg movements, or high level performances in sports. To do so we need to nurish ourselves and provide our body with lots of energy. Breathing properly is important for it provides our brains with oxygen to counter stress and fatigue.
BREATHING WRONG
Half of the population breathes wrong by providing not enough oxygen to the body. The result is a moderate feeling of dullness and fatigue. On the long term this can threaten your brain cells because the brain needs a continuous abundant purveying of oxygen. So breathing wrong can deteriorate or degrade our brain function (on a long term). This has an immediate effect on our focus and concentration, as these things are needed to perform in concentration-related-sports, such as snooker.
Also an inactive life is not contributing to this. The less you stay active, the less lung stimulation to breath deep. A daily thorough air stream into the lungs is very important. Take a stroll for about an hour of go swimming, jump on a bike. Do something!
When having a sitting job it even gets worse as you only use 1/10th of your lung capacity. You start producing less oxygen and eventually your waste material is being drained very slowly. This can influence your temper.
So leading a physically active life is important. It clears up the head as well. Knowing that some of the snooker matches played can last up to 3 hours or more, you need to be top fit. Teach yourself to breathe properly. It will raise your level of concentration and reduce your level of stress.