For war hero Daniel Keighran it could happen at a seemingly unlikely time.
He might find his mind wandering while he is driving.
Cpl Keighran, who was awarded the Victoria Cross, Australia's highest military honour, for extraordinary bravery in Afghanistan in 2010, will drift back to the days he spent trying to stay alive while on deployment.
It was a time of being constantly alert, aware of surroundings, looking for any little telltale sign that danger was imminent, such as disturbed earth which could indicate the presence of a deadly improvised explosive device.
"If I am driving, I still do it sometimes, if I am not paying attention to what I am doing," Cpl Keighran said yesterday.
"All of a sudden I will be looking for disturbed earth on the side of the road or something like that and I go 'idiot'.
"It's manageable for me, I just kick myself and go 'what are you doing?'"
But while Cpl Keighran, now an underground miner in Kalgoorlie-Boulder, says that he is doing all right after his service, he also says too many other veterans are not.
He hopes that speaking of his experiences, as part of his role as ambassador for the Australian Defence Force Assistance Trust, will encourage veterans who are not all right to seek help.
Trust executive officer Allison Stephens said the organisation, set up in 2012, had helped more than 100 individuals or families of veterans.
More than 70 per cent of the help has been related to a mental health issue.
The need can become apparent in any number of ways, such as drinking too much, relationship breakdown, sleeplessness or being unable to pay bills.
And the help can come in any number of ways: financial counselling, organising medical help, covering the cost of a school camp for children of veterans, or something as urgent and basic as a food voucher.
Trust board member and SAS Vietnam veteran Peter Fitzpatrick said that soldiers were part of a family when they were in uniform but after they left the forces they faced a new world without that structure.
"Veterans have to fight for everything they get unfortunately, and that still leaves major gaps," Mr Fitzpatrick said.
"That's why this trust exists."
'All of a sudden I will be looking for disturbed earth on the side of the road or something.'" *Daniel Keighran *