US gymnast Johnson faces 'impossible' Olympic comeback

Around this time of year in America, many parents of 18-year-olds are anxiously watching them leave the nest, head off to college and take on the challenges of adult life. Not Doug and Teri Johnson.

They face very different concerns. But then, Shawn Johnson isn't your average daughter. A life-size bronze statue of her stands in their home town of Des Moines, Iowa.

Her bright smile adorns Coca-Cola bottles and McDonald's merchandise. Recently, in front of millions of people, she strutted her stuff to victory in the US version of Dancing with the Stars.

In a cupboard at home, she has four gymnastics medals from the Beijing Olympics - one gold, three silver.

Doug and Teri look affectionately at the photos and trophies clustered on a wall of their house. They are on an upstairs wall, not in the living room, as Shawn, their only child, "doesn't like it". But there is worry in their eyes. Winning gold at the Beijing Olympics Shawn Johnson's career in pictures

After winning Olympic gold on the balance beam aged 16, she was catapulted into the limelight of American celebrity, endorsing dozens of products, appearing on numerous chat shows and attending countless premieres.

SHAWN JOHNSON ON RETURNING TO SPORT

Shawn Johnson

A comeback in gymnastics is almost impossible in itself. Add to it an injury, why would you even try? It will take even longer, but I like the challenge

Speculation that Johnson's media commitments would prevent a return to Olympic gymnastics was compounded when she tore knee ligaments while skiing. It was something of a turning point though as she vowed to defend her title at London 2012.

Seven months down the line, we are attending one of Shawn's first training sessions in the gym while her parents are coming to terms with their determined daughter's decision to do it all again.

Shawn is postponing college, cancelling all the events on her celebrity schedule and staying at home where she will spend almost every day of the next two years punishing her body in the gym.

"Here we go again," says Doug. "To see her have to do all that practice for another two years, that's tough." Teri nods. "I'm still a little numb," she says. "It's been fairly recent that we realised she's going to do this full-board."

I ask her what the hardest bit is. She replies: "The little bit of lack of confidence that she has this time around, that she didn't have any of last time around. That makes me sad for her ... it will make her stronger, but it's tough to watch."

What does she want for Shawn in the next Olympics? She answers without hesitation. "I just want her to stay happy, that's all. I don't want her spirit to be broken."

Their daughter is an extraordinary performer. She arrives home exhausted after her four-hour practice, which she now does six days a week. The BBC team stands awkwardly nearby as she slumps at the kitchen table to eat a bowl of yoghurt.

Several glasses of milk and some acai chocolate covered blueberries later, her brown eyes begin to sparkle and her warm, honest smile appears.

She leads us excitedly up to her bedroom. At first glance, it's a normal teenage girl's space.

Countless pairs of high-heels, holiday snaps on the mirror, a monochrome picture of Marilyn Monroe. Then there are the Dancing With the Stars costumes.

"Aren't they beautiful?" She picks out a turquoise-tasselled number. "Just look, underneath, it's all covered in jewels."

Removing her Olympic medals from their red velvet cases, she handles them gently, pointing out the white jade on the back of the gold medal. "This is the pinch-me moment," she says. "I still can't believe I'm an Olympic athlete."

I ask her why she's giving up the Hollywood lifestyle and going for London 2012. She really doesn't know why, she laughs.

Shawn Johnson's love of learning

"A comeback in gymnastics is almost impossible in itself. Add to it an injury, why would you even try? It will take even longer, but I like the challenge."

She seems touchingly unsure of herself. She knows the pain she will have to go through. "The hardest thing is not knowing if I'm going to make it."

She confesses to the loneliness she feels. "I'm 18 years old and I'm living with my parents, all my friends are going off to college. Not many people know what you're going through. But if you can get to the end, then it's worth it."

There's a poem printed on a large canvas on the wall above her bed:

"You fear the loss and pain of defeat

but still are able to stand on two feet,

You crumble and cry as much as you want,

but nothing can keep you away from the hunt,

this is what you've been working for,

the pride and honour as you take to the floor … "

It carries on for another dozen or so lines, evoking the difficulties of being a champion. She tells me that she wrote it. She likes my look of surprise.

She then points out a small picture of James Dean and reads out the quote on it: "Dream as if you'll live forever, live as if you'll die today."

I sit on her bed beside her, feeling the weight of her Olympic medals, thinking about the bravery of her decision. I sense that this young woman, half my age and almost a foot shorter than me, is teaching me something very important.