Mark Barden attends Washington Navy Yard memorial service and speaks on ABC's "This Week" panel

A special message from Mark Barden, father of seven-year-old Daniel:

On Sunday, I was invited to attend the memorial service to honor the lives lost in the mass shooting at the Navy Yard in Washington, D.C.

From a few blocks away, the magnitude of the event was evident by the scores of U.S. Navy officers and personnel arriving in full dress.

As we made our way across the lawn and past the families who had lost loved ones, I tried to push my own grief aside. I reminded myself that this was for them, these families. But as the Navy Band began the first bars of "Danny Boy", my feeble wall of altruism crumbled and I was overwhelmed with emotion.

I am these families. I joined this awful club last Dec. 14th when my seven year old Daniel was killed by a gunman in his 1st grade classroom along with 25 other innocent children and educators.

I re-centered my focus on the here and now. I looked at the large group of people whose lives are forever changed. These people now know the inexplicable pain of trying to contemplate the unimaginable. These people will never have an answer to that constantly pervasive "why?' This time, I was able to truly step away, for a moment, from my own tragedy...and let my heart break for them.