Pure and soft air enter our lungs ... sometimes; its a unconscient act that affects us and that we could learn from.
After all, life is knowledge.
Air enters new goes out ...filthy. as well, we born pure and we get unpure as time goes by. There are simply small things that we cross by every day and we just can't notice, sometimes they are pure and other don't. It was worth to spend some time choosing which simple things are around us, so we could move forward easily. So... breathe in and out as simple as it is.... if you have the time for it!