Full breaths allow the fullness of the Universe to operate fully with in us. Shallow breathing keeps us in our comfort zones, where we stay stuck. Check on your breathing from time to time, especially when you're frustrated or tense. Notice the pattern. Start taking long, deep breaths through your nostrils the next time you're in a tense situation, and notice the difference in the shift of how you handle that situation.
Shallow breathing is like working a part-time job.
You can't work part-time and expect to get full time benefits. It doesn't work that way. Plain and simple. If you want the benefits of full time work, then you must apply yourself accordingly. Life is just like breathing.