But Tuesday's newly named mirror ball champ didn't see things potentially heading in that direction until closer to the end of the competition.
"There was a point where I realized I really wanted to win," Riley, 27, standing alongside partner Derek Hough, told PEOPLE inside the ballroom right after landing the show's highest honor.
"And that point was maybe the last time [I had to put needles in my knees]. The last time I got the knees lubed up was the time that I was like, 'Hey, you know, I feel like I really want to win this, so let's go hard' … It was America's vote and they voted for me and I really appreciate it."
Happily for her, staying in the competition all 12 weeks has done wonders for Riley's body – physically, mentally and emotionally.
"I'm a lot stronger," she said. "I have muscles and aches in places I didn't know existed. My clothes definitely fit differently. I feel better as a person. My energy is better."
In fact, when she initially signed on to do the show, improving her body was one of her only intentions for competing.
"At the beginning, I didn't think I was going to win," she told reporters. "When we first started, that wasn't the goal. It really wasn't. I was like, 'Okay, well, you know, it'll be great exercise – it's going to be fun. I'm going to learn dances because I love dancing and maybe I'll look like a dancer and experience something new.' "
Now that she has a shiny disco ball souvenir in her possession, Riley, who plans to use the award as "a centerpiece at Thanksgiving," is "looking forward to sleep because I haven't slept in two months."
And although her two fellow finalists – Jack Osbourne and Corbin Bleu – have also slept equally low amounts, they used their last remnants of energy to congratulate Riley on her big win.
"I'm so happy for Amber," Bleu said. "I'm so happy for them. I'm extremely proud. She's grown so much and she deserves it. She really, really does."
As for Osbourne, he said, "I love that Amber won. Amber every week has just lit up the ballroom, and I know she's clearly been as entertaining to people at home as it has been [sitting] here week after week watching her just slay it. I'm so happy she won."