1. Your heart beats over 100,000 times every single day. Even when you are resting or sleeping soundly, your heart works constantly without ever taking a break. Over a full human lifetime, a heart will beat more than 2.5 billion times!

2. The "lub-dub" sound of a heartbeat comes from tiny valves snapping shut. When a doctor listens to your chest with a stethoscope, the sound isn't the muscle contracting—it is the sound of four internal one-way doors (valves) snapping shut to keep blood moving in the right direction!

3. Your heart pumps enough blood in a lifetime to fill a supertanker. Every minute, your heart pumps about 1 gallon of blood through your circulatory system. In an average lifetime, it moves over 1 million barrels of blood through miles of blood vessels!

4. Fairytale blue whale hearts are the size of a small car. A Blue Whale's heart weighs over 400 pounds—about as much as a bumper car at an amusement park! Its major artery (the aorta) is so wide that a human toddler could crawl through it.

5. Laughter is great exercise for your heart. When you laugh out loud at a joke, your brain releases chemicals that relax the walls of your blood vessels. This allows up to 20% more blood to flow smoothly through your body, reducing physical stress on your heart muscle!

6. Fairyflies have the smallest hearts on Earth. The microscopic fairyfly wasp—which is smaller than a single grain of sand—has a heart so tiny you need a high-powered laboratory microscope just to observe it pulsing!

7. Your heart is roughly the size of your two clenching fists. In an adult, a heart is about the size of one large fist, but for kids, holding your two fists together gives a nearly perfect estimate of how big your own heart muscle is inside your chest!