Endurance running: Shannon-Leigh Litt completed challenge

Shannon-Leigh Litt is used to taking on challenges that would leave most of us distraught.

Try running up to 300km a week training for her favourite event - the 100km endurance race which is more than two marathons in distance.

But the 500km in five days challenge she set herself is the toughest physical and mental thing she has ever undertaken.

The final stage running up and down Mauao turned out to be just too much to do in one day so she finally finished yesterday afternoon on what turned out to be day six.

Mount Maunganui resident Litt admits to being in more pain than she can remember.

"It has been extremely tough, the toughest thing I have ever done, and I have never felt so low on a run," Litt said.

"I was crying a lot of the time and when you are in a lot of pain emotions run high.

"They are right at the surface, particularly when you are running. You are focusing on basic needs like fueling, hydrating, making sure you are in balance. It is particularly important because it is not about winning, it is about surviving and finishing."

Litt says the Waikato Trails run on day three was the toughest of the four different runs.

"I thought the Mount might be the toughest, and it definitely was the longest with the terrain, but the Waikato Trails was tough.

"I had finished the Mount beach run very late and I didn't have a very good sleep, and at the 70km mark there I had a friend support me thankfully because I have never felt so low.

"But you learn a lot about yourself when your mood is low.

"If I did it again I would do things quite differently but it is all experience and I am very happy with the way things have gone."

Litt was grateful to the support she got from the public and particularly from her good friends Kate Townsley and Heather Andrews, who are both long distance athletes. Despite the difficulties she faced, Litt says it has all been worth it as she has raised money for Shine, a national domestic abuse charity, and is ahead in her preparation for a major race in Hong Kong in January.

The 100km event is very similar to going up and down the Mount, with similar terrain.

To follow Litt's progress towards Hong Kong and further, go to www.facebook.com/shannonleighathlete.