Lou Gehrig was so strong and durable that he was called “The Iron Horse.” But a rare disease forced him to leave the New York Yankees in 1939. (Associated Press)

“Today I consider myself the luckiest man on the face of the Earth.”

Lou Gehrig said those famous words on July 4, 1939. They are part of the saddest and bravest story in American sports.

Gehrig was a great first baseman for the New York Yankees during the 1920s and 1930s. That was when baseball was by far the most popular sport in America. Pro football, basketball and hockey were just getting started. Hardly anyone played soccer or lacrosse.

Since baseball is a game of numbers, let’s look at Gehrig’s statistics. They are eye-popping. Gehrig had a .340 career batting average with 493 home runs. He drove in more than 100 runs in 13 consecutive seasons, including one in which he knocked in an amazing 184 runs. Gehrig also scored more than 100 runs in 13 seasons.

Gehrig’s most incredible record was that he played 2,130 games in a row, from 1925 to 1939. That record stood until 1995, when it was broken by Baltimore Orioles great Cal Ripken Jr., who eventually played in 2,632 consecutive games. Gehrig was so strong and durable that he was called “The Iron Horse.”

But in 1939, when Gehrig was 36 years old, everything changed. That spring, Gehrig looked thinner and less sure-footed around first base. He played so poorly that he removed himself from the Yankees lineup because he felt he was hurting the team.

Gehrig went to the Mayo Clinic, a famous hospital in Minnesota, and got some bad news. He had amyotrophic lateral sclerosis, or ALS, a rare disease that attacks the body’s nervous system.

Many diseases are cruel, but ALS is one of the cruelest. Over time, a patient with ALS finds it difficult to walk, speak, eat and even breathe. So Gehrig, one of the country’s greatest athletes, would become more and more helpless.

Gehrig knew he was very sick when he stood before the microphones at Yankee Stadium on Lou Gehrig Appreciation Day (July 4, 1939) between the first and second games of a doubleheader. Surrounded by his former Yankees teammates, including Babe Ruth, Gehrig received presents and good wishes.

When it came time for Gehrig to speak, the quiet first baseman shook his head. But the more than 60,000 fans chanted “We want Lou. We want Lou.”

So Gehrig — a dying man — told the crowd he was “lucky.” He was lucky because of all the good people in his life. His wife and family. His teammates. The Yankees’ owner and managers. The fans. Gehrig even remembered the groundskeepers and other folks who worked at Yankee Stadium.

He concluded by saying, “I may have had a bad break, but I have a lot to live for.”

Lou Gehrig died June 2, 1941. But he is still known as the Luckiest Man.

Fred Bowen is the author of 19 sports books for kids, including nine baseball books. His latest baseball book is “Perfect Game.”