Martin Plowman re-adjusts his sitting position multiple times and pauses to collect his emotions while relaying details of a visit to Walter Reed Army Medical Center in Washington, D.C.

The impromptu Christmas Eve cheer was decidedly tempered by the stark reality of the effects of war.

“Words can’t explain if you haven’t been there. It is very sobering, and if you have an ego this will wipe that right away,” says Plowman, a Firestone Indy Lights race-winning driver who is as engaging off the racetrack as he is focused on it.

Plowman is among the participants in the Indy 500 Centennial Tour – a 10-day goodwill trip to Europe and the Middle East that kicks off Jan. 12 with the goal of boosting morale by bringing the excitement of the 100th anniversary celebration of the Indianapolis 500 directly to more than 10,000 service men and women.

The team, which also includes Indianapolis 500 winners Mario Andretti, Johnny Rutherford and Al Unser Jr. plus Indy 500 veterans Sarah Fisher, Davey Hamilton and Larry Foyt, will give motivational talks and participate in autograph and Q & A sessions led by VERSUS broadcaster Jack Arute, meet and greets, and photo opportunities.

FYI: indycar.com will have regular text, video and photo reports from the tour

The initial stop is visiting with wounded troops at a military hospital in Germany, and Plowman -- who’s about the same age as many of the enlisted men and women serving around the globe -- sought to test his psychological mettle by visiting Walter Reed.

“I would say I was like anyone else going on this tour. I was very anxious about what to expect because we are going out to meet these guys who put their life on the line every day," he says. "They see some terrible things and they make huge sacrifices so that we may walk free.

“The biggest impression I got going room to room – and some of these guys are double or triple amputees – was their optimism for life. They are going through pain that we can’t comprehend. But there they are, laughing and joking and describing their injuries as part of the job.

“One person I met, I’ll call him Mike, said ‘I signed up for my country to give my life and all they took was my leg.’ ’’

On the tour, he’ll have a better understanding of soldiers’ plights and passions, and the knot in his stomach just might be loosened the next time he spends a few minutes conversing with a wounded warrior.

“Not one of these guys felt regret or sorrow for having sacrificed. That was really impactful,” says Plowman, who also is encouraging awareness and contributions to two military-related organizations.

“Our mission for the tour is to meet and greet as many troops as possible on bases overseas to say, ‘Thank you for helping to keep us safe and free,’ ’’ he says.

“In addition to our group mission, my personal mission is to raise $10,000 for two good causes -- Help for Heroes and the Wounded Warrior Project. The money raised will help rebuild the lives of soldiers who have made sacrifices so that we may walk free.”