A little tip from a pulmonary class I'm taking:
When you breathe in thru the nose - let's say for a count of 3!
Then you breathe out thru the purced lips - for twice the count!
Breathing out slowly and completely is important!
This allows the CO-drenched air to expell from the lungs!
You might, at first, feel slightly strange .... because most people, including me, do not breathe right. The benefits are relaxation - and can be proven by measured blood/oxygen levels.
Try it a few times!
Rob & Gizmo