(ABC News) -- Waitresses were always quick to look at 2-year-old Caleb Kinnaird's blue lips and ask if he'd just had a blue Popsicle.
"We didn't always have the heart to tell people he's dying and in heart failure," Caleb's father, Daniel Kinnaird, told ABC News.
But last week, when Kinnaird walked into Caleb's hospital room for the first time after his heart transplant on Sept. 25, Caleb was sitting up in bed and his cheeks and lips were a "rosy pink."
"I'll remember that for a long time," Kinnaird said.
"Basically, they told us we've got his heart started again, but we can't guarantee that he's going to live much longer," Kinnaird said. "My wife and I just kind of sat in a room and cried and came to grips with that news."
So on Nov. 1, 2012, they brought Caleb to Riley Hospital for Children at Indiana University Health in Indianapolis, the only hospital in the state where he could get a heart transplant. He lived there for almost a year while his family lived across the street in a Ronald McDonald House.
Caleb's cardiologist, Dr. Randall Caldwell, said Caleb's heart failure was so severe that doctors couldn't wean him off intravenous heart medications necessary to stimulate his heart function. Because Caleb wasn't getting good blood flow to his gut, he also wasn't able to keep food down, so he "ate" via intravenous nutrition for a year.
Caldwell said he's cared for children like Caleb in the past, but sometimes they die before they can get a new heart. He credits the nurses at the hospital with keeping Caleb alive so long.
Since Caleb was so young, he needed a donor heart about the size of a plum from another toddler, which Caldwell said was hard to come by. Even worse, his blood was type O and he'd developed antibodies that limited his ability to accept most hearts -- even if they were the right size. Caldwell said Caleb would have rejected all but one in six to eight hearts.
"It was like finding a needle in a haystack to find an appropriate donor," Caldwell said.
The waiting seemed to be endless to the Kinnairds.
"Christmas isn't a good metaphor because you know Christmas is coming," Kinnaird said. "Even if it's a year away, it's coming. This is like waiting for something even bigger, even better than Christmas could ever hope to be."
When Kinnaird got the call last week that doctors found a matching heart for Caleb, he called his wife, who is eight months pregnant, and listened as she jumped around, ecstatic. He joked that he had to calm her down to keep her from going into early labor.
After the surgery, they looked at a monitor by Caleb's bedside and saw immediately that his blood oxygen level was 100, instead of the 60, 70 or 80 they were used to seeing.
Now that Caleb's heart doesn't have to race to keep his body supplied with oxygen, he has more energy, too. What's more, he's able to eat real food again for the first time in a year. And it's his new favorite thing to do, Kinnaird said.
"He attacked a blueberry muffin like he was some kind of carnivorous beast taking down an antelope," he said.
The Kinnairds and Caldwell said they hope Caleb's story helps people to better understand the importance of organ donation -- especially for young children.
"All of the sudden, everything changes because somebody, some parent on the absolute worst day of their life decided to give the gift of organ donation, and it absolutely changed our lives," Kinnaird said.