But it's days like Wednesday that make it easier on the 18-year-old from Freedom, Pa., a suburb of Pittsburgh.
By now, the city and most of the country know about Challis' struggle with cancer. It's been well documented in local newspapers and even on national television.
Challis was the Pirates' special guest and was given his own locker and uniform. He made a speech to the entire Pirates team, and joined manager John Russell during the skipper's meeting with the press. His mother, father and several of his friends joined him in section 115 for the Pirates' game against the Yankees.
"God lets everything happen for a reason," said Challis, as he sat in Russell's office chair with cameras and tape recorders surrounding him. "My reason is he thinks I'm strong enough to handle it, so he's using me to spread his message to make the best of things out of life. It's pretty much all I'm doing, is making the best of things in life."
Challis wrote a message on the Pirates' dry-erase board, writing, "Have fun, [it's] the reason why we play ball."
"The reason I wrote that was a lot of times baseball gets blown up so much," said Challis, who has spread his message of courage through assemblies, radio and television for the last two months. "It's made into something greater than what it really is. It's not that complicated. Someone throws it, you swing and you hit the ball. Let the statistics be there, but don't worry about it."
Earlier in the afternoon, Challis was found conversing with first baseman Adam LaRoche, sharing a conversation about hunting. LaRoche gave Challis two camouflaged hats and a copy of the popular DVD, "Buck Commander".
"If we can have the courage and faith just to half of where John has, I think we're all better off," Russell said. "It's a great story. We've been following it for a while now. We've been very excited about this day. The courage that he shows and the message and the unselfishness that's part of his life, I think it's a great message for all of us."
Both Challis and his father, Scott, call special days like Wednesday "stepping stones." It helps ease the pain of cancer that has spread to his lungs, and the many treatments of intense chemotherapy.
"Not once in two years has my son complained about it," Scott Challis said. "[He's] never said, 'Why me?' It's just been amazing. He just keeps speaking from his heart to people. He's just making the best of it."
John Challis has even started his own foundation that is geared toward helping high school student athletes with terminal diseases.
"We just want to help kids," he said. "It's a smaller version of Make-A-Wish."
Todd Krise is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.