Blood vessels (veh-suls): The system of flexible tubes—arteries, capillaries and veins—that carries blood through the body. Oxygen and nutrients are delivered by arteries to tiny, thin-walled capillaries that feed them to cells and pick up waste material, including carbon dioxide. Capillaries pass the waste to veins, which take the blood back to the heart and lungs, where carbon dioxide is let out through your breath as you exhale.

Although you do want to increase your walking over time, this doesn’t necessarily mean that you have to be working your way up to a more intensive form of cardio like swimming or running. “Moving on to new exercises is not something someone should feel they have to do unless their goals change and a new exercise is needed to support those goals,” says Gagliardi. “Walking alone can be progressed by changing the distance, speed, terrain, and by adding intervals.”

Real talk: It could take weeks or months to see the metabolic effects of exercise on the scale, and even then, building muscle, which is denser than body fat, could lead to weight gain. "Do what you like because it’s good for you," Dr. Seltzer says, noting the way exercise is awesome for your heart, mental health, and more—and that not all measure of progress can be seen on the scale.
Here's something else most people probably don't know: Fidgeting is good for you. It's considered a nonexercise physical activity, and it's an important way to burn energy. You get more health benefits if, in addition to exercising, you are a more fidgety, more active person the rest of the day. This means gesturing while you're talking, tapping your foot, just moving around.