Starting in middle age, a man's blood vessels begin to stiffen and his blood pressure often creeps up as well. In everyday terms, this diminished aerobic capacity can produce fatigue and breathlessness with modest daily activities. That's why a healthy 25-year-old heart can pump 2½ quarts of blood a minute, but a 65-year-old heart can't get above 1½ quarts, and an 80-year-old heart can pump only about a quart, even if it's disease-free. After age 25–30, for example, the average man's maximum attainable heart rate declines by about one beat per minute, per year, and his heart's peak capacity to pump blood drifts down by 5%–10% per decade. Some of the changes of aging start as early as the third decade of life.
Here are some things that aging can do to you - if you give up and let Father Time take his toll. For men who manage to avoid major medical problems, the changes are slow and gradual, but they do add up. The clock ticks for all men, and with each tick comes change.