In March 2006, the same day De Williams ran in the Commonwealth Games Queen Baton Relay in Melbourne[2] she was diagnosed with breast cancer.

After treatment, De Williams founded the charity Running Pink and embarked on another circumnavigation of Australia on foot,[3] to raise funds for the National Breast Cancer Foundation.

In Nov 2010, De Williams was awarded Tasmanian Australian of the Year 2010[6] by the National Australia Day Council for her athletic achievements and fundraising efforts.

In Jan 2015, De Williams was awarded a Member of the Order of Australia, for significant service to the community through contributions to a range of cancer support organisations, and to ultra marathon running.

[15] After tripping and sustaining an injury to her feet, on 6 June 2009 at GPS co-ordinates S 13° 03.130' E 131°06.663', De Williams ended her attempt to run around Australia after 224 days and 10,824.8 km.

[16] De Williams had raised over $100,000 for the National Breast Cancer foundation and became the first female to run from Hobart to Darwin.

[21][22][23] De Williams continued back down the east coast of Australia, along the same route she travelled on her first attempt.

[24][25] During her run De Williams experienced extreme heat, a tropical cyclone[26] on Christmas Day 2010 in Townsville and the 2010-2011 Queensland Floods.