As it says in the Royal Marines' recruitment adverts, 99.99 per cent need not apply.
It seems like a strange way to encourage people to join, but if someone tells me not to do something then I'm twice as likely to try it.
I'm told this is because I am stubborn and have a 'healthy disrespect for authority' - neither of which would seem like ideal qualities in a Royal Marine.
But, according to Major Simon Fuller, project officer in charge of the current recruitment drive, the advertising campaign is working.
"Since the launch of that slogan, the success rate of applicants has gone up. Our recruits are given 32 weeks of the hardest and longest training in the world.
"We want people who will rise to the challenge. The people who think 'I'll join the Army instead because it's only 13 weeks of training' wouldn't make ideal Royal Marines.
"It's not a job - it's a way of life. My men are on the road at the moment and they are working Monday to Saturday and spend Sunday travelling, so they won't have a day off for six weeks."
Still not put off, I agreed to take part in a recruitment day at Sutton Park, where young people undertake a series of gruelling mental and physical activities designed to give them a taste of life as a Marine.
The recruitment drive is the first of its kind by the armed forces and those participants who show potential are encouraged to apply to join up.
My first task was to join a team on a rigid-raiding craft, a 240-horsepower speed boat used to take commandos off ships and into combat.
This sounded easy enough so I was happy to climb into a dry suit, usually worn by a 6ft Marine in the freezing fjords of Norway.
I then discovered why the Marines are known as the Royal Navy's amphibious force - not because they are trained in combat on both land and water, but because the dry suits make people look like giant deformed frogs.
I was told to sit at the front of the boat and naively assumed this was the safest place to be. Five minutes later I was almost submerged in freezing cold water as the two-and-a-half tonne boat spiralled round at 40 knots. I held on for my life and survived, relatively unscathed, but nursing a broken fingernail.
This activity has proved to be the most popular with recruits, followed by 'close quarter battle' - more commonly known as paint-balling. When I've taken part in the past, the intention has been to cause my opponents as much pain and cover them in as much paint as possible. This time it was a bit more organised.
The Marines had built a wooden village and recruits were given an extensive brief on how to attack it. They were then furnished with guns and paint capsules and had to launch an attack on huts defended by the Marines themselves.
Next was target practice with live rifles.
Major Fuller said: "It's quite strange for a lot of people to pick up a live weapon and start firing at a target for the first time and they get quite nervous. The girls have proved to be better at it than the boys." The other thing that the girls were proving to be better at was rock climbing and abseiling. I happily threw myself off the top of a 50ft wall holding on to a rope and was told I did the best abseil of the day, without a hint of sarcasm. Honestly.
"Six people in every 40 refuse to do the abseil" said Major Fuller. I felt quite pleased with myself, until he added: "My 62-year-old mother-in-law did it last week."
I was a wimp when it came to the unarmed combat task and didn't volunteer to be thrown around by a Royal Marine who was wider than I am tall.
I was put off by his repeated use of the phrase 'testicles as earrings' but I learned a lot and there's no chance of me having my handbag pinched.
Recruits also get to ride in the Viking, a new armoured vehicle which is the most capable and mobile vehicle of its kind in the world.
Maj Fuller said: "It puts less pressure on the ground than a man, so it would hurt more if I stood on your foot than if it ran you over." I didn't volunteer for that, either.
Sadly, I wasn't asked to join up, but I've convinced myself this was because of my gender, and not my 'healthy disrespect for authority'.