What if you had to think about every single breath? You would never sleep deeply, never lose yourself in a daydream, never focus fully on a conversation. Thankfully, you do not have to. Right now, as you read these words, your respiratory system is performing an invisible miracle. It is pulling oxygen from the air, swapping it for carbon dioxide in your blood, and doing this about 20,000 times a day without a single conscious thought. Every breath you take is a transaction.