Former SAS corporal Chris Ryan knows how to survive.
He escaped 300km across the Iraqi desert during the 1991 Gulf War, worked undercover in Northern Ireland and faced rioting mobs in Central Africa.
In his new book Safe, Ryan gives practical advice on spotting a con, staying safe on holiday and how to know when it's time to run or time to hide.
Ryan was inspired to write the book after a horrifying off-duty moment a couple of years ago when he got "a phone call no parent would want to receive".
Scotland Yard's anti-terrorism branch informed him that his adult daughter was been actively targeted by a terrorist cell.
It was a completely alien experience to feel so powerless, Ryan says. All he could do was sit there and rely on other people while imagining the worst.
"I felt quite inept. It was horrendous. I was just worrying all the time."
His daughter is now safe, but the fear from such an experience is "like bloody cancer", he says.
"It's in remission but it could come back at any time."
Although our individual chances of being caught up in a terror attack are low and we shouldn't allow terrorism to change the way we live, Ryan says, it's good to be prepared.
If you're in a situation and the fight-or-flight response kicks in, if you can, take two seconds to gather your thoughts, he says.
"The first thing soldiers are taught – you go down to make yourself a smaller target, you locate the danger. That will then dictate where you go to cover."
Ryan's tips on the best places to hide come straight out of the SAS standard operations procedure manual, he says.
The bottom line – choose a place another human being wouldn't want to go, then keep very still. (This works in both rural or urban environments.)
"It could be an industrial dumpster full of trash, a grotty part of a wood or the side of a ditch that would be wet and nasty."
Ryan's street safety tactics were honed on surveillance jobs in Northern Ireland when his life depended on them.
"If you're walking down a street and somebody's looking at you, you glance away and you look back and they're still looking at you, I would immediately look at their hands, see what's in their hands. At the same time I'm looking at their clothing – are they carrying anything? Do they look normal? Is he or she still looking? Then you make a decision – do you look over? Do you cross the street? Do you put some gap between you?"
Walk facing the oncoming traffic if possible, and be aware that if you've got headphones on and you're checking your phone you've blinded and deafened yourself, Ryan says.
He would never risk walking through a city with headphones on himself.
But even Ryan has learnt hard lessons from careless everyday moments.
Arriving in Barcelona for a long weekend years ago, he was tired and went straight to his hotel room.
At 2am, fire alarms went off and the main lights and emergency exit lights went out.
If it had been an actual fire, Ryan would have perished in the 15 minutes it took him to get out of the hotel, he says – a lesson on the importance of checking where the fire exits are in any new space.
Pulling off the longest-ever escape and evasion by an SAS trooper – on the ill-fated Bravo Two Zero mission during the Gulf War – wasn't "one blaze of glory", Ryan says.
After watching a comrade die of hypothermia, he was nearing despair when a piece of his mum's advice came back to him – 'If things get on top of you have a good cry'.
He tried to cry but ended up laughing and it helped clear the clouds. "I knew exactly what I had to do – walk 40km every night."
The worst parts of his escape were during the day when he had to lie still yet shivering on rocks in high windchill and below-zero temperatures.
Sleep deprived, with toes oozing pus, septic bedsores all over his body and receded gums, by the seventh night Ryan was hallucinating, collapsing and felt like electric shocks were going off in his head.
"To be honest, I don't think I had another day in me. I think I would have perished if I'd been a day short of that border."
Knowing there was no help coming, the only thing to do was keep going, he says.
"The choice is you lie there and die or you get up and start walking … When things start coming down on you, you realise how sweet life is, actually. you've just got to fight and keep moving – and that was the only choice I had."