Now this is cool. Another electron microscope image, this time of your lung tissue. The red things are capillaries, which wrap around your lung cells, or alveoli. I think of them like little clusters of grapes.

Take a deep breath. When we breathe in, the “grapes” fill with air. Oxygen goes into the capillaries and off to all tissues of the body. CO2 goes the other way, coming out of the body. Like car exhaust, we exhale that back into the world. Then trees take a breath of IT!
When we exercise, we grow more capillaries into the lungs, making us more efficient at oxygenating our tissues. It’s like tuning up a car!

So get off your ass!