Cardinals running back Elijhaa Penny carries the ball against Washington.

Speaking something into existence can be a motivational tactic, but this was borderline reckless.

Elijhaa Penny is in his second NFL season, and a quadriceps injury to Kerwynn Williams could vault him into a starting role for the first time on Sunday against the Giants. Penny called it a potential "opportunity of a lifetime" this week, but, notably, he didn't consider it pressure.

Pressure is sitting unemployed for a week while your mother beams with pride, believing her son was already in the NFL.

"I told my mom that I was signing a contract," Penny said, "just so she wouldn't worry."

After rushing for 1,159 yards at Idaho as a senior in 2015, Penny waited expectantly to hear his name called in the 2016 draft. That didn't happen, and to make matters worse, no team offered him a spot on its 90-man roster as a rookie free agent.

Sure, the Cardinals called with an offer to try out for their team, but the odds of getting signed off that were small. After Penny hung up from that conversation, tears flowed down his face as disappointment swirled inside him.

But before he could get a word out, Penny looked over at his mom, Desiree, who had interpreted those tears as elation.

"Everybody thought I was crying because I had made it," Penny said. "I was hurt. Everyone was depending on me, and I was crying because it was just a tryout. But my mom started crying because she was like, 'You made it.'"

Penny saw the joy radiating from his mom's face. He probably should have told her he was not in the NFL. But he couldn't.

"I'm like, 'Man, I don't want to spoil her moment and be like, 'Mama I didn't make it,''" Penny said. "So I went with it. Like, 'You know what? I made it.'"

For the next nine days, Penny was a fake Cardinal. During that span, he decided not to tell his mom the truth, instead becoming intent on turning the lie into reality.

"Me and my fiancée, we went to the beach (in Los Angeles) and I told her I wasn't coming back (after the tryout)," Penny said. "That was a lot of pressure."

Penny arrived in Arizona for the three-day audition and narrowed his focus. In his mind, he didn't need to outplay all the other rookies. Just Jared Baker, the running back the Cardinals signed after the draft.

"No offense, but I just wanted to look better than him at everything," Penny said.

After the final practice, the rookies who were under contract went into the weight room to lift. Penny, meanwhile, got dressed in an auxiliary locker room, where panic suddenly set in.

That may have been the final carry of my life. It might be time to become a trucker like Dad. My lie will be discovered.

"I thought that was it," Penny said. "I started thinking about my mom. But one of the scouts came in and he's like, 'Elijhaa, come upstairs.' And everybody's like, 'You're going upstairs! You're about to sign.' I wasn't trying to (get excited) until I signed the thing, until it was official. And then Mike (Iupati) came and congratulated me."

Penny not only made the offseason roster, but defied the odds by nabbing a practice-squad spot. He remained there for all of 2016, and then took the next step this season, making the active roster as the fourth running back.

His role was supposed to be special teams, but injuries have decimated the position. Penny had 10 carries for 45 yards last week against Washington after Williams went down, and he could be the primary ballcarrier on Sunday.

"I've liked him since being able to call preseason games and being able to just feed him the ball," offensive coordinator Harold Goodwin said. "If you guys remember the Denver game two preseasons ago, I think he had (113) yards rushing. He's a hell of a back. He's got a lot of upside. He's got a heavy head. There were a couple times he ran over (Washington safety D.J.) Swearinger last week. Swearinger was tackling his ankles. I like him. I really do. He works hard."

Penny is stoked for his opportunity. He knows many players have put together impressive careers despite being undrafted. He feels like the biggest hurdle has already been cleared.

"I put a lot of pressure on myself to come out here and get an offseason roster spot," Penny said. "That was the hardest part. Now that we're playing football, this is the easy thing now. Everybody knows I can play. I know I can play. Now I just need to go out there and put it on film."

Penny still hasn't told Desiree his fib, which, thankfully, has turned into nothing more than a white lie.

"I don't want to tell my mama," Penny said. "I don't want her to worry. She doesn't understand how (the process) goes, so to my mom, I made it."

Should the stars align on Sunday, Penny can tell her of his unlikely rise from fourth-stringer to impact performer.

If he hasn't already.

"You hear stories like this all the time, how he was undrafted, trying out or whatever," Penny said. "And they finally get their shot. This is a big opportunity for me. Don't go in there nonchalant. You can change your life with this opportunity. It would be an amazing journey if I go in there and capitalize on what I can do."