Ever since he stayed in the first Monastery, Tyson has always made sure to regulate his breathing. In through his nose then out through his mouth, even when he's just walking. It's the technique used when he meditates.
He does this because of several reasons, the most important being it causes him less pain when Sebastian injures him. This works because it puts less stress on his ribs as he breaths.
The second reason is that it keeps him calm, meaning that his head is more clear and he can come up with a better way to address a situation even if he is angry or upset it allows him to think properly.
The third reason is that it allows him to feel some control. Since he met Sebastian he's had very little control over his life and controlling his breathing lets him feel as though he has some control.
He does this because of several reasons, the most important being it causes him less pain when Sebastian injures him. This works because it puts less stress on his ribs as he breaths.
The second reason is that it keeps him calm, meaning that his head is more clear and he can come up with a better way to address a situation even if he is angry or upset it allows him to think properly.
The third reason is that it allows him to feel some control. Since he met Sebastian he's had very little control over his life and controlling his breathing lets him feel as though he has some control.