We have the power to breathe in oxygen and breathe out carbon dioxide, since the day we were born. It is what keeps us from living.
Being able to manage your breath in difficult situations is powerful.
Whenever I am down, I slowly take a few, deep breaths.
It reminds me that I cannot control the outcome. Keep moving forward
For instance, my jump shot in basketball is not falling. I take a deep breath.
(My younger-self would be upset. I would never want to settle for a jumpshot anymore. For the reason that, I was never confident with my jump shot.)
My good friend practices meditation daily. As he meditates, he focuses on his breath. He recommends me it.
He has physically, mentally, emotionally, and spiritually grown as a person. Also, he has developed a sense of mindfulness. (He once had a "fragile" ego.)
In general, breathing clears your mind, especially if you meditate, like my good friend.