Marcus Smart has a job that often requires him to take charges from players 4 inches taller and 40 pounds heavier. After his Celtics played six games in nine nights, he was tired and sore.

But as he finished his shooting drills, he got himself in the right mood for a charity event he was hosting at the team's practice facility for Children's Hospital patients and their families.

The plan: a video game extravaganza for the patients, who arrived with delight to find Xbox and PlayStation consoles set up around the court. Soon Smart was feeding off the energy of the beaming kids, while the children reveled in a fun NBA respite from the needles, chemotherapy and drudgery of being chronically ill. For a few hours at least, things were a little fun.

The afternoon was winding down, and Smart was satisfied his day's work was complete -- until, while everyone was packing up, he was approached by the brother of a patient named Damone.

Damone, the world's biggest 16-year-old Marcus Smart fan, was hospitalized with lymphoma and was devastated he was missing this day because he was too ill to leave the hospital.

Smart looked at his watch. It had been a long day, but what was one more hour? He drove to Children's to meet Damone, who, his family explained, had been listless and despondent and hadn't left his bed for weeks. Damone had undergone a bone marrow transplant, and his prognosis was dire. He had lost hope, addressing his family in monosyllabic tones.

"He was really struggling, really depressed,'' Smart says. "He wouldn't talk to anyone.''

But when Smart strode into his room, Damone came alive. For the first time in weeks, he sat up. He recited Smart's high school statistics from Flower Mound, Texas, and even rattled off the names and ages of Smart's brothers.

One of those brothers, Todd Westbrook, a former all-district player from Lancaster, Texas, was diagnosed with cancer at age 15. He battled his illness for nearly two decades and died at the age of 33, leaving behind a heartbroken younger sibling. Smart says Todd's resilience has remained a driving force in his own quest to become an NBA star.

Maybe the death of Smart's own brother from cancer is what moved him to reach out to Damone. Maybe that's why the two of them were able to talk so easily and so frankly.

"I don't know how to describe it,'' Smart says. "You know when you have a special connection with someone that you can't explain? This little guy did it for me.''

Smart visited with Damone for nearly half an hour. He chatted with him about basketball and about his illness. They talked about Todd Westbrook and his courage in facing his disease. Damone hung on every word.

"It was the first time the doctors and his parents had seen any positive reaction from him in a long time,'' Smart says.

It was a long day of practice, drills and charity events, but another hour at the hospital was time well-spent for Marcus Smart. Darren McCollester/Getty Images for Boston Children's Hospital

The following day, on Friday, Jan. 22, Smart and the Celtics played host to the Chicago Bulls. He arranged to have pizza sent to Damone's hospital room while he watched the game with his parents. Smart wrote Damone's name on his shoes and dedicated the game to him, which the Celtics won 110-101.

After the game, Smart motioned to Heather Walker, senior director of public relations of the Celtics, and gave her his sneakers.

"Make sure Damone gets them,'' he told her.

Walker called Children's Hospital the next morning to arrange for the shoes to be delivered. What she discovered took her breath away: sometime during the night, after the pizza party and the Celtics victory, Damone had passed away.

The news left Smart sobbing like a small child. Nearly a year later, the mention of Damone's name still leaves him fighting back tears.

"I think about him a lot,'' Smart says. "I wish I could have done more.''

Damone's death has left Smart more resolute about understanding pediatric cancer and its unique challenges. The physicians at Children's allowed him to visit their stem cell research center, where Smart learned neurologists have developed a low-cost test to detect tumors, a welcome alternative to the pricey CT scans that are often difficult for families to afford. Smart was fascinated to discover there is a 3-D model of the brain that physicians practice on before they actually operate on their young patients.

None of it can bring back his brother Todd or his pal Damone, but there will be more kids just like them, and Smart promises to be there for them.

"The one thing I do take out of it, is for that one night, I could make Damone laugh and smile,'' Smart says. "I think that's all he wanted -- to have one more kid moment. I thank God I had the chance to give him that.''