As you get older, your heart gets slightly larger. Its wall thickens, and it may pump less blood. The aorta, the main artery from your heart, gets thicker and stiffer, and your other arteries thicken too. As tissues in your blood vessels become less elastic, your blood pressure goes up.

More than half of Americans over age 60 have high blood pressure. However, that does not mean it is part of normal aging, warns the National Institute on Aging. Blood pressure changes all the time depending on physical activity, your emotional state, diet, medication, and whether you're standing, sitting, or lying down.

As you age, you breathe in a little less oxygen. Your lungs lose elasticity and some of their function, and you're more vulnerable to some infections. The muscles you use when you breathe tend to weaken. Exercising and breathing at high altitudes, where there's less oxygen, may get harder. But if you don't smoke or don't suffer from lung damage or disease, you probably won't notice significant changes in the way you breathe during most day-to-day activities.