During a Tuesday appearance on Good Morning America with his Dancing with the Stars professional partner Sharna Burgess, Johnson explained, "We were together about three-and-a-half weeks. I would probably say this was harder than football."
"Football is just natural for me. I mean, I lost 20 pounds in three-and-a-half weeks. [Sharna and I] probably averaged at least four hours a day in training. [One day], we had rehearsal from like 9:30 [in the morning] to midnight before the show on Monday."
Johnson, a retired NFL football player, then elaborated on why dancing posed more of a challenge for him than his favorite sport.
"It really is harder than football because the comfort zone that you're in in football -- it's something that you've been doing since you were little," he said. "Now all of a sudden, you're a grown man and you're like stepping into this, and these guys are like [5 foot, 9 inches], 145 pounds and you're 230-plus pounds, and you're trying to move like them. It's totally different."
Johnson surprisingly told the GMA co-hosts that prior to his stint on the show, he didn't speak with any fellow NFL players who competed on Dancing with the Stars before him.
"I didn't speak to anybody -- nobody. [I] wanted to learn for myself because the format was totally different for them when they were in. They kind of changed everything, so it's totally different," Johnson noted.
Johnson was apparently more confident in his own dancing skills and ability to learn the ballroom steps than Burgess was.
"Every single day she was stressed out, and I was like, 'Don't worry, I got it! I got it!' And she's like, 'No you don't have it! No you don't have it!'" Johnson said.
Burgess then insisted, however, that Johnson worked "so, so hard" and was completely dedicated to memorizing and practicing her choreography. The pro dancer added that he was "full of personality" on the dance floor, which she didn't expect at first.
Looking forward to the rest of the Dancing with the Stars season, Burgess said the competition amongst the remaining 11 couples is going to be fierce.
"The cast this season is insane. And we have some incredible, incredible talent from Week 1, you know?" Burgess explained. "We really have some talent this year that have dance experience. So that makes it quite amazing for us and what we're going to see. I'm really excited for it. I think our finale is going to be just epic."