As the family ate orange chicken, chow mein noodles and fried rice, Josh decided that going blind was bad enough, and that he didn't want his family to be distraught about it.
"I realised that the best way to cope with going blind was to be positive," he said.
He also realised that he had a lot to see in a short period of time - he had never seen the ocean, the desert or a mountain vista. And that's how his bucket list was born.
Now he's racing to take in as much as he can, while he can.
Friends and family members have responded, raising more than US$41,000 so far through a GoFundMe account to help the high school student see the US before he completely loses his sight.
A couple of weeks ago, he and several friends went to Missouri to watch his favourite baseball team, the St Louis Cardinals, play in Busch Stadium.
Since Josh's diagnosis on September 15, he has spent time on a beach in Northern California with his family and visited the Golden Gate Bridge, marvelled at the Sierra Nevada mountains and the soaring granite cliffs of Yosemite National Park.
He also took in a Chicago Bulls game. Plans are now underway for trips to the Grand Canyon and Niagara Falls, and he also hopes to see Mount Rushmore and the northern lights, and possibly go white-water rafting and skydiving.
But most of all, Josh said he wants to play basketball for one last season with his high school team, the West Chicago Community High School Wildcats.
"There's nothing I love to do more," he said. "I've played basketball since I was in the third grade."
Leber's hereditary optic neuropathy causes the rapid disintegration of the optic nerve, "like a TV cord that's been chewed on by a mouse," according to the United Mitochondrial Disease Foundation.
Although Josh still has peripheral vision in his left eye, "I can't see what's right in front of me," he said. Sometime in the next few months, his doctor told him, that blurry vision will spread to his right eye, and by March, he probably will be 90 per cent blind.
"Like lots of people, I took my eyesight for granted," Josh said. "I'm grateful to have a chance to see what I can in the time I have left."