BLACKSBURG, Va. — First lady Michelle Obama said during a commencement speech Friday that she admired Virginia Tech's resilience in the face of violence on the campus violence, including the 2007 massacre that left 33 dead.

"I know that as one of your commencement speakers today, I'm supposed to offer you all kinds of wisdom and advice and life lessons. But the truth is, like so many people across this country and around the world, I have been following the journey of this school," Obama said.

She addressed a crowd of about 35,000, including more than 5,000 graduates, at Lane Stadium in Blacksburg. She led the school's call-and-response cheer of "Let's Go! Hokies!"

"I have witnessed the strength and spirit of the Hokie Nation," she said. "And I think that you all already learned plenty of lessons here at Virginia Tech."

She said Virginia Tech students have demonstrated the close community they've built, their service to others, and their joining together to chart their future. Graduates should go out and create their own new communities, including attending town hall meetings, school assemblies and reaching out to new neighbors or those in need, she said.

She also spoke about her personal experience with the healing power of helping others.

"Years ago, I went through a similar process in my own life" at the age of 26, Obama said, after one of her best friends died of cancer and her father died of multiple sclerosis.

"For months, I felt like I couldn't breathe," she said, recalling memories of her father and how hard her parents worked to provide for her family and help her and her brother attend college.

"And as I grieved, I came to realize that the best way for me to honor my dad's life was by how I lived my own life," said Obama, who said she quit her job at a big Chicago law firm and ultimately started a community-based nonprofit that helped young people.

Obama told graduates to follow Virginia Tech's slogan, "Invent the future," by charting their own course in life.

"The truth is, there will be people who judge you based on one isolated incident," she said. "People can only define you if you let them. In the end it's up to each of you to define yourselves."

She noted that Norris Hall, where a gunman killed 30 people before committing suicide in 2007, is now Virginia Tech's Center for Peace Studies and Violence Prevention. And the dormitory where the first two students were slain has been renovated into a residential college. And, for the first time since the slayings, classes were held on April 16 this year.

Obama told graduates that they shouldn't let others define the school by the tragedy.

When asked, "Isn't that the school where ..." Obama offered the students several possible responses.

"You tell them, 'Yes, it's the school where we produce graduates who are leaders in their industries, and pillars of their communities, and who carry their Hokie pride with them every day for the rest of their lives.'" She said. "You say, 'Yes, that is the school I attend. That is Virginia Tech.'"

U.S. Sen. Mark Warner also spoke at the ceremony, noting that the university has gone through "great moments of celebration and awful moments of reality."

Warner, D-Va., also advised graduates to learn from their failures as well as successes, and "call your mother" and others who encouraged and supported them along the way.

"You can even use a cellphone," Warner said, giving a nod to the industry that made him a wealthy man. "Every time you do that, I hear 'ch-ching, ch-ching.'"

Obama's appearance in Blacksburg comes less than a week after she and President Barack Obama appeared at a rally in Richmond to kick off his re-election campaign. Virginia is considered a battleground state in the presidential election.

Virginia Tech was the first of three spring commencement addresses for the first lady. She also plans to speak at North Carolina A&T on Saturday and at Oregon State on June 17.

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