By Russell Sharp
Russell Sharp prepares for life at Catterick
When the BBC asked me to go undercover in the British Army to investigate bullying, I had to think long and hard.
The Army is one of Britain's most secure institutions.
Up until then I'd been working with school children around Leeds. It felt like an impossible ask.
I took a deep breath and agreed to do it, to test the government's promise to take better care of recruits after the Deepcut scandal.
It's important because these are the young men and women who get sent to fight wars, keep the peace and deal with disasters.
I had three months to get ready.
I had to get used to using secret cameras and have my cover story word perfect. As it turned out the most effective secret camera I had was the one in my mobile phone.
Several BBC training courses, and lots of practice later, it was time to join up.
On 21 October 2007, I left my family home and made my way to my new home - a barracks in the Infantry Training Centre, Catterick Garrison.
I was leaving family and friends who knew I was joining up but not as a BBC reporter, and stepping into the unknown.
That day was so intense that it's all a bit of a blur.
The corporals were suspicious of me at first.
I had more qualifications than most infantry recruits, but I just followed orders and kept my head down.
My life became waking up at 5.30 or 6am, impeccable ironing, constant cleaning, tight timings and lots of marching.
At least that's what I was doing when I wasn't getting army fit.
Joke comes close to uncovering truth about reporter
My back, legs and arms have never hurt as much as the times we had to run with a huge log over hills for a couple of miles.
Carrying a fake casualty through the wind and rain was no easier.
Then there was marching quickly for miles carrying what was effectively a small house on our backs.
Battle fitness training is what makes an infantry soldier.
On exercise there were massive highs and lows too.
Freezing cold, soaking wet, crawling though mud and staying up all night with little food takes its toll.
But then something as simple as a warm sleeping bag, a bite of food or the sun rising can really cheer you up.
I never forgot why I was there; I had to be the best recruit I could be while at the same time investigating whether the Army had kept its promise to stamp out bullying.
In my platoon I saw two corporals lose their temper and break the rules, punching recruits or grabbing them by the neck and throwing them to the ground.
One recruit was even urinated on by a corporal as he lay prone waiting to fire his loaded rifle.
It was hard finding the time and opportunity to investigate what was going on in my own platoon.
Even harder in a sister platoon, where I was beginning to hear some worrying things about the way their recruits were being treated by three of their corporals.
For the first six weeks I had little free time and was escorted everywhere around camp by a corporal.
With few opportunities to gather evidence, I had to take every chance.
On the live firing range I saw a corporal smash two recruits' helmets together and kick one of them.
Russell Sharp on reaching the end
Another grabbed recruits by their helmet straps and shook them hard. I was one of them.
I also got the chance to speak to some of the lads in the other platoon.
One told me he was kicked and punched by a corporal.
Another describes being punched to the ground by one of his instructors. He says his hand was injured as he tried to defend himself from further blows.
He told me fear of this kind of behaviour affected his concentration when learning, including how to use his rifle.
Training has to be tough but if a recruit can't concentrate on learning how to use his rifle, how is he supposed to help protect himself and his other comrades in a real fire fight?
For six months I did two jobs at the same time. Reporter and soldier.
Right up until the moment I actually walked out the gate for the last time after being discharged I still thought I might be discovered.
One wrong look, one wrong hand movement at the wrong time and it could all be over.
Even now I struggle to believe that I actually managed to get in and out of the British Army without being discovered.
The Undercover Soldier will be shown on BBC One (except Northern Ireland) on Thursday 18 September at 2100 BST.