Battling dehydration, stomach illness, monsoonal weather, bad air quality and injury, Samantha Gash ran close to 3,200km west to east across India's most punishing terrain.
Gash started from one of the driest deserts on earth, Jaisalmer in Rajasthan, traversed the chilly foothills of the Himalayas and completed the marathon in Shillong, Meghalaya.
The marathon was all about raising funds for World Vision Australia projects tackling barriers to quality education.
Gash was first female and youngest person ever to complete RacingThePlanet 4Deserts Grand Slam Challenge in 2010. In 2011 she completed a 222km nonstop run in the Himalayas and it was on this run that she decided she would commit her life to running for change. She has since run 379km across Australia's Simpson Desert and 1968km across South Africa for Save the Children.
Gash told The Huffington Post Australia one of the most magical parts of her latest challenge was running up the foothils of the Himalayas.
"The landscape was incredible, the energy of the people and how I personally felt completely shifted from the mental and physical harshness of the central Indian plains. Highlights included being able to experience Diwali with my Indian team and turning 32 on a highway in Bihar. These were moments I will never forget," Gash said.
"It was amazing being invited into strangers homes all across the country and learning about them, their family and community. In those visits we spoke about their challenges, their hopes and even their fears. This was such a privilege that would not have been possible if it were not for collaborating with World Vision."
Gash had to deal with illness and injury along the way but she had expected her body would go through a significant adaption period early on.
"It's not normal to push your body in this way in those types of extreme conditions that I faced in the Rajasthan desert. Because I had prepared myself for this, I was able to mentally have the patience to let my body go through whatever it was going through. There was one 10km stretch in the second week when I really felt as though I was cooking myself from the inside," Gash said.
"I didn't realise at the time but I finished that day holding my belly. That night my stomach blew up and it was a sign that my body was shutting down. I really had to slow down my pace for a few days, I had no choice."
"I only focused on one day at a time and had short term goals of reaching Jaipur, Delhi and Pauri -- which took me through the first five weeks of the project. After this point my body really was in a much better place."
World Vision Chief Advocate Tim Costello has applauded Samantha's amazing run and believes it will have a ripple effect on many people.
"Samantha began this epic journey with a deep desire to use her passion and talent to make a difference in the lives of some of the world's most vulnerable children. Her completion of this awe-inspiring run across India is a reminder to us all of what can be achieved when we have determination and an open heart," Tim Costello said.
You still have a chance to make a donation to Run India until January.