But it was Nelson's own battle with cancer over a year ago that took his appreciation to another level.
"I thought it was scary," Nelson said of his experience. "I can't imagine what it's like when a kid has cancer. It's nice to be able to show someone that you care. There's a limit on the number of visits we can do because of the finances, and it would be great if we could increase the number of kids that we could reach with this program."
Increasing the finances was why more than two-thirds of Major League umpires took to the links at the McCormick Ranch Golf Course on Thursday. Over 150 golfers joined foursomes that included not just umpires, but also some Major League players such as Russ Ortiz, Matt Herges and Will Ohman.
"There's more people that get involved each year," umpire Bruce Dreckman said. "The more we're able to get the word out, and the more people realize what we do, it's only going to get better."
Among those who volunteered their time on Thursday was former Major League All-Star and current D-backs television analyst Mark Grace, who was invited to the event by umpire Joe West.
"I always had a good relationship with the umpires," Grace said. "I always looked at it like we were in things together. At the end of the day, you have arguments and disagreements, but we're all out to make the game better. They do a great job with their charity and I was glad to come out here and help them in any way I could."
As part of the event, there was a silent auction of items that included an autographed George Brett vintage Royals jersey, a framed autographed Nolan Ryan jersery, a hockey jersey autographed by former NHL great Wayne Gretzky, and a home plate from the 2009 World Series and All-Star Game autographed by the umpiring crew and MLB Commissioner Bud Selig.
Many Major League teams donated VIP packages for the auction. The packages included tickets to a game as well as an invitation onto the field to watch batting practice and meet a player.
One of the more unique items was a round of golf with NFL legend Dick Butkus, and the best timed item was an Arizona Cardinals helmet signed by wide receiver Larry Fitzgerald Jr.
The event and auction help fund the two major programs for Umps Care Charities. One is the hospital visits, and the other is Blue Crew Tickets, which provides tickets to children who are awaiting adoption, and single-parent families.
Sometimes, the mascot for the local team will join the umpires during a hospital visit.
"It helps us during the season because it brings you back down to earth and reminds you what is important in life," Nelson said. "You see the kids in the hospitals, and you see the looks on their faces when they get a bear or the mascot comes in, that makes it fun, and helps you realize what's important. It makes you proud of being an umpire because you're channeling the contacts and the nice people that you meet on the road into something positive and productive."
Nelson visited a children's hospital in Boston in September along with the three other members of his umpiring crew and Red Sox mascot Wally the Green Monster. Among the patients they saw that day was a young girl named Joanne.
"She had tubes and wires all over, but she thought it was the coolest thing in the world to see the Red Sox mascot, and to get a bear and be able to pick out a uniform for it," Nelson said. "If you don't get choked up over something like that you're not human. She was the happiest person in the room. It was just amazing."
Umpires have similar stories when it comes to the Blue Crew Tickets program. The organization partners with the Dave Thomas Foundation for Adoption and Big Brothers and Big Sisters of America to provide tickets and a goodies bag as well as a chance to walk on the field with an umpire.
"I just love looking at their eyes when we come out of the tunnel and they see the grass and players are out there taking batting practice," umpire Ted Barrett said.
"Sometimes a player will come over and say hi. You can tell it's a big thrill for kids. That's the type of stuff that really excites me and makes all this work pay off."
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.