Transcript for The final lap: Danica Patrick on her journey to NASCAR stardom and why she's retiring
Reporter: I usually, Danica, any time I'm riding shotgun I say, Jesus takehe wheel, please. But you might be the next best thing. Oh, thanks. Reporter: So I'm not too worried. I'mlad you trust me. You mate not say so when it's all said and done. Reporter: Danica Patrick is theueen of speed. Whether ladin laps at the daytona 500, or running 220 miles per hour in an indy car, the 5'2" auto racing pioneer is the most storied woman in American motorsports history. He's done so well at daytona -- Reporter:ut this weekend, Danica is hitting the brakes on her career, retiring at 36 years old. So I'm do at 36. I have a chance to do so much more. It wasn't in my heart anymore. You know, wt I love about racing was that ability to progress and get better. And I just kind of felt like that was becoming less and less some that was in my control. The fir driver to colete -- Reporter: Her final race at the Indianapolis 500, on T track that brings her career full circle. It all started with her first indy 500. As a rookie. She won rookie of the year that year in 2005. And that was the start of the phenomen known as Danica mania. Reporter: A household ne that became a marketer's dream earning her majorndorsement deals from the likes O Coca-Cola, even opi nail Polish. Nothing happened. That's Danica Patrick! Reporter: Don't forget about risque super bowl commercials for her long-time sponsor godaddy. "Forbes" listed daica as the eighth highest paid driver in NASCAR, earning $10.23 million la year. A long way fromer days in roscoe, Illinois, where she began racing go-karts at 10 years old. I know that I loved coming in after making Aun and asking what my lap times were. To see if I had gon faster. Reporter: At 16 she dropped out of hh school to become a race C driver in England, moving back to the U.S. Three yearsater working her way up to indy car and NASCAR circuits. Move over! The lady is coming through! Danica Patrick wins at twin ring! Reporter: With nearly 400 races UND her belt,he's only won E race, at the indy Japan 300 in 2008. The critics who said she oy won one indy car race? That's true. And that's true. They simply said, oh, she just wasn't that goo of a driver. People have been saying that my whole career. What impact did that have on you? None. When I was younger, I used to get really angry and look really angry. Because I never wanted anyone to think that I was okay with fourth or sixth O tenth. So I used to sort of project that iecurity out througmy face. I don't thin it was very pretty. You also had a few fights. I'm sure that I've started some fights. But for the most part, I tend to -- I feelike I'm very respectful of people. Reporter: In November, after facing sponsorsh changes, Danica announced she was taking her last ride. Sohis will be my la season as a full-time driver. My sister told me I was supposed to -- Reporter: She set out to complete T final races dubbed "The Danica double." Since 2015, godaddy return as her sponsor. But in February Danica's final spin at daytona ended with a crash. Slammed into the wall! Are you kidding? Reporter: Finished in 35th place. Danica Patrick -- Reporter: A few weeks ago we followed Danica around godaddy before head to company headquarters in Tempe. Danica Patrick! Reporter: Surprising a few employees and devoted fans with tickets to her final race. Oh my god! Yes, yes! Reporter: In H post-racing life, Patrick plans oning more time to focus on her growing business empire. Which already includes a clotng line and a wine label. They're amazing companies and passions of mine. So if I kept racing 40 weeks a year, for how long, I mean -- they don't get the attention thats needed to see them to their fullest potential. Reporter: She's also a ess fanatic, even writing a health and wellness book. On Sunday, Danica Patrick takes the wheel for her final race. Hoping to take the checkered flag at the Indianapolis 500. She'll be the only woman in the race,eaving behind the sport where she has been such a trail blazer. I choose to foc on the positive and I've had a really great career. I'm really thankful for it. Reporter: For "Nightline" I'm Marcus moo in Scottsdale, Arizona. You can watch Danica's last la in the Indianapolis 500 Sunday at 12:00 noon eastern here on ABC.
This transcript has been automatically generated and may not be 100% accurate.