Good breathing is healthy breathing. Breathing helps to maintain and improve both your general physical health and your mental and emotional well-being in the following ways:

Boots your energy and stamina.
Counters tiredness and can reduce your need for sleep.
Relieves tension in your body and enhances your ability to deal with pressures and stress.
Brings a sheen of vitality to your complexion and eyes.
Boots your immunity and releases chemicals that promote healing.
Increases your powers of concentration and ability to think clearly.
Brings calmness and mastery of your emotions.
Maximizes your verbal delivery by strengthening your voice and clarifying your thinking.

Source:
The Art of Breathing Well For Harmony, Happiness, and Health by Swami Saradananda.