Air Force Col. Ed Hubbard arrived in Vietnam on June 20, 1966. He was captured and imprisoned in Hanoi on July 20, 1966, just 30 days after his tour of duty began. He spent the next 2,420 days as a prisoner of war in and around the capital of North Vietnam.

During more than 6 1/2 years in captivity, Hubbard and his fellow prisoners devised methods to not only maintain their sanity amid constant mental and physical stress, but to emerge from confinement in better condition than when they entered.

Motivational speaker

Retired from military service since 1990, Hubbard now travels around the world 200 days a year to spread his message about the boundless potential of the human mind, citing his experience as a POW as proof. He has spoken to about 1.5 million people in 11 countries as a motivational speaker.

Hubbard will speak at 7:30 p.m. tomorrow at the Parkville Veterans of Foreign Wars hall, 8123 Harford Road. The event is free and open to the public.

He will speak on the subjects discussed in his book, Escape From The Box: The Wonder of Human Potential, encouraging his audience to "try a little bit harder and get a few more miles out of life."

Writing in code

Hubbard did just that in his time as a POW, using a simple code to communicate with his fellow prisoners. With the code, American POWs could spell out messages to each other by tapping the walls.

In this way, the soldiers taught each other languages, solved difficult math problems and memorized long poems.

"You had to communicate to survive - it was a very critical part of our lives," Hubbard said.

Although each person is born into a particular "box" made up of race, height, IQ and place of origin, Hubbard says these innate restrictions should not limit the potential of each person.

"We are not short of resources," Hubbard said, "we're short of imagination."

The speech is sponsored by Edward Jones Investments.