For three months, Newsbeat followed a group of young men and women training to be soldiers in the British Army.
We saw pain, exhaustion and tears. Some of the recruits didn't make it at all.
The Army desperately needs more young people.
Its own figures show it has fallen below the required number of troops for nine out of the last 10 years.
This is the story of 19-year-old Courtney Biro.
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Around a year ago, she was three stone heavier and working in an office administration job in Huddersfield.
Now she knows how to use a bayonet, fire live ammunition and survive on no sleep. She's been gassed in training, dragged men through mud and spent six weeks in a hospital bed.
"There'll always be that person who will never try.
"I've always been that person that thinks if I can do it, I will do it, it doesn't matter if I'm a woman or a man," says Courtney.
But it hasn't been easy.
First she had to get fit, with the help of her dad.
"He literally dragged me out around Huddersfield, making me run everywhere and just got me ready for it."
Courtney (on the right) with her cousin Rachael in 2014
After signing up, Courtney had to go through 14 weeks of basic training at Pirbright Barracks in Surrey.
By week four though, something had gone wrong.
Courtney had developed an abscess in her back and needed to have surgery.
"It was horrible. Obviously I was in a bad place anyway, totally new people totally new staff. I got put into Gold [section] where all the injured soldiers go.
"At the time I wasn't happy but looking back it was for the best.
"I got put into recovery for six weeks then put back to week one," she says.
"It's been a lot easier this time round. Everything has been different being with the new girls and new training team."
Courtney hopes to join the Royal Signals as a communication systems operator
Recruits at Pirbright are taught the basic skills in being a soldier and after spending 27 weeks there, Courtney knows what her strengths are.
"I quite enjoy fizz [physical training]. I mean I'm not the best at it but I put in 100%.
"I do enjoy the [firing] ranges - it's just when you're firing it's not very nice.
"What I found hard was being on exercise, being on stag [lookout] in the middle of the night, when they come and get you and you just think 'I don't want to do this'.
"Probably the worst day of us being here, we'd had bayonet training, exercise, been gassed and had no sleep - it was just mentally challenging.
"A few years ago I would have never seen myself being here.
"I've always seen myself as very girly with make-up and hair - I never thought I'd get to this point."
Squaddies at ease - Courtney with fellow recruits on a rare weekend off
The second time round, Courtney made it through the full 14 weeks injury free and went into phase two training with her regiment.
Of the six recruits Newsbeat followed, Courtney was only one of two people who completed the training.
"After you've done it, you're so proud of yourself.
"They gradually build you up but just little things you learn to deal with which make you a better person.
"Your patience goes up a lot higher but there are some days where you can't handle it."
After completing phase two Courtney will be fully ready to start work, with every chance she'll have to go on tour and even face enemy forces.
"I don't think you can ever be prepared, until you're out there. I don't feel physically ready for it but I do feel mentally ready.
"My parents are really proud, especially my dad. I wouldn't have been able to do it without him.
"I wanted to be out there, I wanted to make a difference and I think I'm doing that in the Army."
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