Breathing as a tool
Here are some tricks with the breath which I learned during yoga and vipassana.
Energize
Inhale long and as deep as possible, exhale short/quick.
Relax
Exhale long and fully, inhale shorter yet slowly.
Warm up the body
Exhale hard and quick through the nose. (kapalabhati)
Inspiration for this post:
https://aeon.co/essays/do-hold-your-breath-on-the-benefits-of-conscious-breathing