This is not about necessity. This is about a desire built off a work ethic instilled in him by his father, a laborer, who at the age of 63 still wakes up at 4:30 a.m. to go to work and usually gets home about 4:30 p.m.
"The way I was raised, you earned your money," Harrison said. "My dad has always worked hard and never quit on anything. The same with my mother. I have to repay what they did for me. I can't quit, either."
So even though he had a multiyear deal that would have paid him $41 million even if he had never thrown another pitch after undergoing the surgery last summer, Harrison couldn't take the easy way out.
On Tuesday night, Harrison will make his second start of the season for the Rangers, looking to prove he still belongs. And he will be taking the mound against the Rockies in Coors Field, which can be a problem even for the healthiest of pitchers.
"If you get the ball up, it can go a long ways here," Harrison said with a smile.
Doesn't matter to Harrison. He wants to pitch, and wherever his turn comes up in Texas' rotation, he welcomes the opportunity.
Oh, how easy it would have been for Harrison to just walk away. In the aftermath of an 18-win season in 2012, he signed a five-year, $55 million contract. Harrison made only two starts the next season before back problems that flared up in Spring Training sidelined him.
"The day after I had a Spring Training game, I was out running sprints, and when I took off, I felt a pop and then a burning in my hip," Harrison said. "It got worse and went down my leg."
Harrison underwent therapy that summer and then made four starts in 2014 before finally giving into the back ailment.
"We tried rehabbing, but it didn't work," he said. "Doctors went in and cleaned up the discs twice. It didn't work."
Surgery became the only alternative. It came with risks. Former Angels third baseman Dallas McPherson is the only known baseball player to return after the surgery, and it was a limited return. Back problems cut his 2006 season short after 40 games, and he played only 22 games after that -- 11 with the Marlins in 2008 and 11 with the White Sox in '11.
"He made it back, so I know there is a chance," said Harrison.
Harrison knows it won't be easy. It has been a challenge just getting to where he is now.
"The [Rangers] didn't count on me, but things really progressed in April, faster than I thought, and I was able to get on the mound," he said.
And Harrison has continued to move forward.
The numbers aren't pretty. Harrison made six starts between Double-A Frisco and Triple-A Round Rock in preparation for his return to the big leagues, and he was 1-3 with a 6.23 ERA. In his return to the Rangers against the D-backs on July 8, Harrison gave up six runs on six hits and three walks in registering 12 outs.
The confidence, however, remains.
"I made four starts [in extended spring camp] before I went to the Minor Leagues and that was about getting a feel for being on the mound, working on [pitcher's fielding practice], breaking off the mound," said Harrison. "Those games were getting used to it again. Now it's about getting the job done.
"I am feeling good now and it seems to be better as time goes on. It's a learning experience. I have to get the job down with the same velocity. It's about being aggressive. I watched [Mark] Buehrle [in Toronto], and he's throwing 84, 85 [mph] and dotting the I. It's fun to watch. You have to deal with it. It's about getting the job done."
And that's what life has been about for Harrison since he was growing up on 25 acres in Stem, N.C., a town of "about 200 people when I was growing up," that had a population of 463, according to the 2010 census.
"We had a wood stove and I used to chop wood all winter," Harrison said. "There were always chores to be done. We had a big vegetable garden, five acres, where we grew our produce. My dad wouldn't buy a big tractor. We had a tiller I used, and three hours into the day, my arms were numb. But it was a job that had to be done."
Just like for Harrison pitching in the big leagues is a job, and it has to be done. He is not about to quit, even if his money is guaranteed. He wants to earn his keep.
"I won't walk away," Harrison said. "The Rangers are going to have to make that decision."