OAK GROVE, Mo. — An Oak Grove, Missouri family will be celebrating their first Christmas without a beloved husband and father.

Brian Williams, 48, died in September after suffering a brain aneurysm. He and his wife own Fred Williams and Son Heating and Cooling.

Brian’s co-workers say he was as funny as he was knowledgeable, routinely pulling pranks.

“He had a very good sense of humor,” said Artimus Millet. “In the mornings on jobs, you knew it was going to be tough when he said, ‘It’s a piece of cake.’ Someone you never want to forget.”

Brian’s wife, Annie Williams, will never forget this day three months ago.

“On September 29, which happened to be the anniversary of our first date, I could not get a hold of him,” Williams said. “He had calls to go on, and I couldn’t get a hold of him to tell him where to go or anything, and I knew something was wrong.”

Williams called his co-worker, Madison Moore.

“When we got to the location, I was thinking of a joke to tell him like, ‘man you’re in trouble, boy, your wife’s trying to get a hold of you,’ but that wasn’t the case,” Moore said.

Brian Williams died in an empty apartment on a job.

He was born with arteriovenous malformation, known as AVM. In Brian’s case, the blood vessels in his brain formed incorrectly, and tangled. It’s a rare condition with fewer than 200,000 cases per year.

Brian took medicine and had surgery but declined a recent procedure.

“The world was robbed,” Williams said. “He was a great man. His customers call me for him to come over and I have to tell them he died, and they cry, too, on the phone. So, imagine getting call after call and having to say it over and over that he passed, and having them cry. It’s tough.”

Family says 300 people attended Brian’s memorial, and a lot of them were customers. His best friend, Chris Bryant, says that shows his impact.

“A lot of times it was more than a service call, sometimes it was getting down with the customer and talking about life itself,” Bryant said. “They loved that, so they’d always call him back.”

This holiday season, this family wants everyone to remember what’s important, as they celebrate their first Christmas without Brian Williams.

“Just remember, it’s not what’s under your tree, it’s who’s around it,” Williams said. “Just hold your family tight, and kiss them, and love them. That’s important.”

FOX4 told you in November when thieves stole thousands of dollars in tools from Bryant’s work truck. Despite that, and Brian Williams’ death, Annie Williams said the company is doing well, crediting their customers.