Justin Timberlake's date with a Marine combat instructor on Saturday night was one of the most moving evenings of his life, the singer-turned-actor said on his Web site.

Keeping his promise to Cpl. Kelsey De Santis, Timberlake donned formal wear to escort her to the Instructor Battalion Marine Corps Ball in Richmond, Va.

In a post on his site Sunday, Timberlake noted that he was almost brought to tears during a video tribute to Marines.

De Santis, who practices mixed martial arts, invited Timberlake to the event via a YouTube video in July.

She was inspired to reach out to him after he publicly encouraged Mila Kunis, his Friends with Benefits co-star, to accept a similar invitation from a serviceman.

You want to call out my girl Mila? De Santis said to Timberlake in her video. Well, I'm going to call you out and ask you to come to the Marine Corps ball with me on November 12.

She added, If you can't go, all I have to say is, cry me a river.

Timberlake said in his post that he and De Santis had ample time to chat before the evening's ceremony, and that she spoke of her training in mixed martial arts with a passion, a discipline, and a respect. He was struck by her concern with his comfort at the ball.

I have to tell you, it's not every day that I meet a 23-year-old girl and she's more worried about if I'm having fun or if I'm comfortable! Timberlake wrote. It hit me all of a sudden that these were the type of people that look after us and our freedom... Last night changed my life and I will never forget it.

A military wife who attended Saturday's event at the Richmond Convention Center told local news station WTVR that Timberlake posed for pictures and seemed like a normal guy.

Kunis, meanwhile, will attend a Marine Corps Ball with Sgt. Scott Moore on Nov. 18 in Greenville, N.C.