'I just hit a wall where I couldn't see a future,' he said.
'It makes you realise how precious the time you have with your family is, how precious the time with your children is, and how all our time is finite.'
Leigh added that he has fought to not let his tragedy take over his life, and with the help of his four-year-old son, Hugh, continues to raise awareness of brain cancer.
As well as raising money for brain cancer awareness, Leigh has started training for the Hawaiian Ironman, a gruelling race consisting of a 3.8km swim, a 180km bike ride and a full 42km marathon swim, bike race and marathon.
It was always Sara's dream for her husband to compete in the Hawaiian Ironman. When the race organisers heard Leigh's story, they offered him an honorary spot.
Leigh will compete in the race on October 13, in honour of his late wife and son.