Then his world came crashing down around him.
Austin, whose father coaches AAU basketball in Utah, was working out in Dallas with former Jazzman Mo Williams, preparing for the upcoming draft. On Saturday, as Austin trained in the gym, doctors called his family with distressing news.
Immediately, they packed up and made the nine-hour drive from Kansas City.
Austin was in the car with his high school coach, returning home from a barbecue with Williams, when he noticed the familiar cars outside his house in Dallas.
"I remember asking [my coach] what was up and he couldn't even look at me," Austin said.
He walked in the door and saw 10-15 people. There was his Baylor coaching staff, his pastor, close friends and his family.
Almost immediately, Austin knew.
Earlier, doctors had told him he could have Marfan Syndrome, a connective-tissue disorder. That would explain his vision, his long limbs and the stretch marks on his body.
Austin hadn't been given the results, but when he saw his family he knew.
"The first person's face who I saw was my mother's," Austin said. "She was all the way in the back. I just remember seeing tears falling down her eyes. My dad's arms around her. I knew right then exactly what it was because I remembered in Chicago they said I could have had this syndrome and they did blood work on it. I just hadn't gotten the results back.
"I wanted to break down and cry, but I didn't because my little brother and sister were in the room. I wanted to show them that I could be strong for them and for my family because they look up to me."
That night, he didn't sleep.
"It was devastating," he said.
The syndrome means that some of Austin's cells are not fully developed. He has an enlarged aortic artery, which will require open-heart surgery if it continues to grow.
"Playing basketball was a risk to me because, if my body exerts too much energy, I can pump too much blood," he said.
Just days before the draft, his dream was stolen.
After announcing he could not continue playing, there was a wave of support from players across the country. The NBA invited Austin and his family to Brooklyn, to be Silver's guest at Thursday's draft.
Then, midway through the first round, Silver surprised Austin.
His name was called.
He walked across that stage, shook the commissioner's hand and slipped a cap on his head.
"I forgot about the syndrome for a while," Austin said.
But Austin doesn't want to be defined by it.
"It's been crazy," Austin said of the last week. "My emotions have been from sad to the happiest I can be just a few minutes ago. I'm still happy, and I'm thankful for it. These past couple days have really taught me a lot about myself. They've really shown me that no matter what obstacle you're thrown in life, there's always a way through it. There's no reason somebody should hang their head or not have confidence in themselves doing something. So for the rest of my life, I'm going to keep a positive attitude and I'm not going to take anything for granted because it can be ripped away from you in seconds.
"I was having a great day before I found out the news, and everything that I've grown up to know and love was just taken from me. But's really just one of the biggest blessings of my life because it did save it."
He plans to finish school at Baylor and said he could envision himself coaching some day. It's all part of a new dream for the future.
"What's next?" a reporter asked him Thursday night at Barclays Center.
"Everything," Austin said.