While at Benton Community High School in Van Horne, Iowa, Hennings became an All-state football tight end and the state heavyweight wrestling champion his senior year.

That 1985 season was the greatest in Air Force history as the Falcons went 12–1, were conference co-champions, defeated Texas in the Bluebonnet Bowl and placed fifth in the final coaches poll.

ENJJPT is an elite program, and when his ground training studies faltered (he had been an honor student at AFA), his squadron commander isolated him from all contact regarding the Dallas Cowboys, who had drafted him in April 1989.

[3] Because of his military commitment (originally 8 years because he chose to fly), he dropped in the 1988 NFL draft until the Dallas Cowboys took a chance and selected him in the eleventh round, with no indication of an early out from the Air Force.

[5] After the 1991 Gulf War, the United States military underwent an across the board reduction in budget and Hennings was able to have the remaining four years of his active-duty commitment (service academy and rated pilot) waived, which was unprecedented at the time.

In 1992, he left the U.S. Air Force and joined the Dallas Cowboys as a 26-year-old rookie, playing on special teams and quickly becoming a key reserve, on one of the best defensive line rotations in the NFL.

While his play on the field was very good, it was his attitude, character and leadership that was also valuable to the Cowboys teams of that decade, contributing to the top ranked defenses of the early nineties and winning 3 Super Bowls in 4 years.