The University of Texas student and Bangs native is biking from Austin, Texas to Anchorage, Alaska over the span of two months next summer.
"I thought she was crazy," laughed her mom, Sharon Petty, on Wednesday morning.
But the intense training -- and fundraising -- starts right now.
"I know it's not going to be easy, I know it's not going to be a breeze and I don't expect us training to make it any easier," Brittany Petty said.
But there's a greater cause pushing her to pedal.
"I ride for my grandpa and my dad."
Her father is a ten-year cancer survivor, and that's not the only way the disease has touched the Petty family.
"My grandpa died of cancer and he's the one who taught me how to ride a bike so in a way, I'm continuing to fight his fight."
Known as the longest charity ride in the world, the journey is backed by Texas 4000, an organization made up entirely of UT students.
The goal is to fight cancer with every mile -- each rider raises at least $4,500 -- with the money going toward research.
"Research is the cure for cancer," Sharon Petty said.
For her, it's a long and sometimes scary road ahead, but nothing she thinks her determined daughter can't handle.
"Brittany's doing this to help people and I believe she can do it, because it's worth it," she said.
A worthy cause, an iron will, and with the names of everyone she's riding for etched onto her bike -- Brittany Petty begins the long journey she hopes brings a cure closer to reality.
Copyright 2015 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.