For Jim Giaccone, not a single day has passed since Sept. 11, 2001, without thinking of his big brother, Joseph Giaccone.

“Twenty-one years. Twenty-one seconds. The anger is still there. The pain is still there. The grief is not something you check off a list and finish. It’s the new normal,” Giaccone said.

Joseph worked at Cantor Fitzgerald on the 103 floor of the North Tower.

“At 8:46 a.m. he disappeared. We have no remains,” he said. “My brother was hitting his stride when he was murdered. He was 43 years-old. He was a good family man. A great father, he was a better cook than me, but I’m a better golfer, so it evened out.”

Giaccone tried to fill the gaping hole in his heart by channeling his pain into a powerful tribute.

“Either you get bitter or you get better. I strive to always get better,” he said.

He started volunteering with Tuesday’s Children, an organization providing long-term support to victim’s families since 2006.

“I became a mentor, like a big brother. My first pairing was with two young boys. They were six and eight back in 2006. And I still, last week I went to dinner with them. And they’re men now,” Giaccone said.

Another painful loss for the family members is the 9/11 Tribute Museum closing its doors. The museum said last month it will transition to an online memorial — citing financial hardship.

“Breaks my heart. It was just recently closed. It was a tremendous outlet for the public and for my mental health to come and be able to tell my brother’s story to people who were here to listen to it,” Giaccone said.

And with an entire generation of young people not born yet on Sept. 11, 2001, Giaccone’s life mission is to ensure they understand what happened that day and that his big brother will never be forgotten.