"I was pretty confident in what I had done at home," he told reporters Wednesday. "I didn't expect to miss my goal."
The contestants had been challenged to spend two weeks at home, but were promised immunity if they lost five percent of their body weight. Cornelison was only 1 lb. short of his goal, but because he was the only member of the Black Team to fall short, he was sent home by default.
"I was devastated knowing that my journey there was done," he says. "Knowing I would have to [finish my weight-loss] at home where I had just seen that I didn't do that well."
Cornelison, 19, was not the only one saddened by his elimination – his father, Mark, wanted to leave in his place and his trainer Bob Harper told him he was "like a son" to him.
"It's a really complicated relationship," Cornelison says of his special bond with Harper. "Many times he would slip out of trainer mode accidentally if I was in pain or something. He'd be, like, 'I thought that was my son right there on the ground and I don't want to see that.' "
But leaving both his father figures at the Ranch when he returned home to Magnolia, Texas was exactly what Cornelison needed to continue his journey into adulthood.
"I can't have my dad fight all my battles for me," he explains. "I think [being eliminated] was a huge turning point for me. I can go out and do this on my own and I have the confidence enough to say, 'I can take on the world.' "
Cornelison has currently lost over 85 lbs. which has proven beneficial for not only his health but his romantic life as well.
"I'm more energetic so [my girlfriend and I] can hang out and do things. I'm not depressed so she wants to be around me more,” he notes. "Not to mention I look a lot better so she wants to show me off to everybody."
The weight loss has also improved Cornelison's ability to perform with his band My Side of the Story.
"It used to make me really nervous to get up on stage. I'd get really sweaty and run out of energy," he says. "But since coming home I have tons of energy. By the end of the show I just want to keep going."
Gearing up for the finale weigh-in, Cornelison will be documenting the remainder of his weight-loss journey on The Biggest Loser website, something he hopes will inspire others to take control of their lives.
"Week by week people can see my struggles, my highs and lows. It is a lot harder at home but people can still do it," he says. "If I can lose as much weight as I've lost then anything is possible."