According to sociologist Christopher Lasch, Americans often view their 40th birthday as the beginning of the end. And with the recent explosion of midlifers--12,000 a day now turn 40--this makes for a multitude of anxious people. But 40 does not signal the end to productive living; it never has. Want some proof? Consider these examples.

In 1775, Patrick Henry urges the Virginia Provincial Convention to arm its militia for defense of the colony. His words become the battle cry of the American Revolution: "Give me liberty or give me death."

In 1977, Janet Guthrie becomes the first woman driver to qualify for the Indy 500. The next year she is the first woman to complete the prestigious event, finishing ninth and defeating some of the world's best drivers.

At 10 p.m. on April 18, 1775, Paul Revere leaves Boston on a borrowed horse to warn patriots of the British advance on Lexington. When the King's troops arrive on April 19, they find minutemen waiting.

In 1903, Henry Ford forms the Ford Motor Company. Five years later he produces the Model-T and changes the pattern of American life.

On August 18, 1807, Robert Fulton pilots his steamboat, "The Clermont," on its maiden voyage up the Hudson River. Average speed is 5 mph.

In December 1776, George Washington leads his troops across the icy Delaware, launching a successful surprise attack against British-backed Hessian soldiers.

In 1891, Thomas Edison invents the kinetograph camera, technology that becomes the forerunner to the modern motion picture.

In 1924, Nellie Ross becomes Governor of Wyoming, the first woman governor in the U.S. At 53 she becomes the first director of the U.S. Mint.

In 1984, drag racer Shirley Muldowney blows a front tire at 250 mph, breaking her pelvis, right hand, and five fingers. Two years later she returns to racing, posting her career-best time and finishing 10th in the overall national standings.

In 1911, Madame Curie becomes the first two-time winner of the Nobel Prize for her discoveries in physics and chemistry.

In 1926, Eleanora Sears, known as America's first sportswoman, walks from Boston to Providence, RI in nine hours and 53 minutes.

In 1610, using the newly invented telescope, physicist and astronomer Galileo Galilei discovers the four bright satellites of Jupiter. He dubs them Medicea Stars after the Medici family who rule his Italian province.

In 1835, frontiersman-politician Davy Crockett leaves his native Tennessee for Texas and the Alamo. His last fight for freedom will be his most glorious.

In 1884, Mark Twain publishes The Adventures of Huckleberry Finn, his best-selling work and arguably the most influential American novel ever.

 So despite what you may have been told, life doesn't end at 40. Nor does it end at 50. Click here, and I'll show you.