Seven years ago, motocross star Ryan Dungey had a change of heart.

His grandmother died from liver cancer in 2005, leaving Dungey, then 15, an emotional wreck. He was sad. He was angry. He was confused. Repeat.

"I didn't know why," Dungey said. "I didn't understand."

But in the midst of a dark period in his life, the Belle Plaine native found clarity -- a wakeup call of sorts.

"It put things into perspective for me," Dungey said. "All the things that I thought were important didn't seem so important at the time. I grew up. It showed me how quickly everything could all be taken away."

The following year, Dungey made a life-altering decision. He forewent his sophomore year in high school to become a pro motocross/supercross racer in 2006. Six years and seven motocross and supercross titles later, he's in position to win his second motocross championship in three years after his fourth consecutive AMA pro victory last weekend in Michigan. Heading into Saturday's event in Millville, Minn., he sits atop the leaderboard with a 72-point lead.

"What's interesting about Ryan is that he didn't dominate as an amateur coming up," said Devin O'Brien, lifestyle marketing manager for Target, which oversees Dungey's sponsorship. "The manager that gave him his first pro contract saw certain potential but most importantly saw a kid that understood how much work it takes to become a champion. You can't just get there on talent alone."

Since turning professional, Dungey aimed to conquer the motocross world and did. At 22, his trophy case is bulging with hardware.

His accolades include championships in AMA Lites supercross, 250 and 450 motocross and AMA supercross, which placed him among elite company. He joined supercross rider Jeremy McGrath -- Dungey's idol -- as only the second rider in history to win the AMA supercross championship as a rookie in 2010.

Thus, in the motocross world, Dungey is synonymous with winning. But, as he enters his seventh year riding professionally, Dungey wants to be defined by something else -- his philanthropic work.

"Of course I want to repeat the success I've had in the past," Dungey said. "But I see myself moving on to the next chapter in my life -- helping those suffering from cancer and the families going through that tough time."

His success has provided him with the means, paving the way for sponsorships and the money needed to organize charity campaign such as the River-to-River Ride on Sunday. The event, co-hosted by Target, will send proceeds to St. Jude's Children's Research Hospital. Dungey is also an active advocate for Nike's LIVESTRONG campaign for cancer awareness.

"I know what it's like to experience a family member suffering from cancer and losing them to that battle," Dungey said. "I want to help any way that I can."

His charity work also serves as a small token of gratitude and appreciation for the support his grandmother provided him before she died. It's his way of repaying her.

"She meant so much to me," Dungey said. "I'm glad I was able to spend so much time with her before she passed."