'My perspective on life is different now'

"I'm a perfectionist, you have to be as a world-class athlete, and I always want to do things 100 per cent right, so, to be honest, I'm like that as a mother sometimes. I have to rein myself in because every mother learns babies do things at their own speed and in their own time, which Reggie's pretty good at reminding me," she says, smiling as she recalls a 'tomato-gate' episode when her son made it clear he wouldn't have it on the menu despite her best efforts.

"Even my husband, Andy tells me to 'chill out' and that there's really no need to sit there watching Reggie eat every mouthful making sure he gets what he needs. Being a bit of a control freak, I want to do everything for him properly and I put pressure on myself. But really, like every mum, I just want to be the best I can be and give him the best start in life."

The 30-year-old has already proved she's proficient at juggling motherhood and her extraordinary career. The latter began when she was ten years old and her mother, Alison, a charity worker, took her to a summer sports camp in her home city, Sheffield, where her natural talent was immediately spotted.

Since then, Ennis-Hill has become a national icon for winning gold for heptathlon at the 2012 London Olympics, and remarkably won gold last August at the Beijing World Championships when Reggie, born in July 2014, was only 13 months old. "That win at Beijing was fantastic because it was so hard getting back into shape and training after he was born. I started when he was four months old and it was a shock to realise that, after being so used to my body performing at a certain level, it was going to take time to get back up to speed. It took a year for my body to settle," she says.

"It didn't help that Reggie didn't sleep through the night for the first nine months. We've always cared for him ourselves and not had a nanny, so at one stage I was sleep-deprived and questioning, 'What am I doing? Do I actually want to do this at all now I have child?'"

Her will-to-win triumphed though. "I realised there was still this other side of me that's fiercely competitive who wants to achieve and so it's about trying to balance that with wanting to spend as much time with Reggie as possible," she explains frankly.

"One of the great things is that my perspective on life is different now. I've organised training around his needs - it's a no-brainer that he's a priority - so I go out in the morning, spend the afternoon with him, and then do another session when he's asleep in the evening.

"One of the bonuses is, if I have a bad training session, I don't dwell on it like I used to because I'm too busy rushing home to look after my amazing little boy who's smiling and needing his mummy. It balances everything out and has benefitted my performance."

While clearly besotted, she acknowledges that 'guilt' as well as joy is part of a mother's lot. "When he was born, my mum said, 'You're a mum now, you'll feel guilty for the rest of your life', and I completely get that," she declares.

"That can range from worrying I haven't done a tiny thing right for him, to absolutely hating leaving him behind for two weeks to go to Beijing. That was the hardest thing I've ever done. We FaceTimed every day, but it still felt awful and I felt I had to return with a medal to make it worthwhile.

"Mum told me while I was away he used to toddle up to the TV screen when he saw me and say, 'Mama'. That just undid me and melted my heart. This time we're planning for him to come with me to Rio which will be wonderful. My family will look after him and I just won't see him on the days I compete."

Surprisingly, Ennis-Hill, who's supporting P&G's nappy brand Pampers Little Champions campaign, says she's not feeling the same pressure to succeed that she experienced in 2012.

"It was nerve-racking and stressful competing in London because it was my first Olympics. Also, I was competing as a favourite and expected to win, so anything less would have been failure," she says.

"Although I'm going to Rio to perform my best and hopefully go out on a high, especially as it'll be my last Olympics, I don't feel as much outside pressure this time, which is making me much more relaxed. I've been fortunate to have had a great career so far and I just want to enjoy this unique situation which I'll never have again in my life. It'll be even more special having Reggie as part of it. It's great that he's growing up around sport and I hope it will be a natural part of his life."

There has been one experience she definitely didn't enjoy - in January she marked her milestone 30th birthday. "I hated it. It was that feeling of not being really 'young' anymore and thinking, 'Gosh, I must be grown up', which was weird because in some ways I still feel 18, and I train with girls in their twenties," says the athlete, who will decide whether to retire after the Olympics or continue for another year to compete in the 2017 World Championships in London.

"It was silly to mind about it because I'm so happy with my life and feel very lucky to have my husband, Reggie and my career and everything going so well. I do find it hard, when I look back, to believe I am where I am now. I sometimes don't feel that different from the little Sheffield kid who just loved running, especially because, although things have changed for me so much since I've won medals and become well-known, the rest of my life's stayed the same," says Ennis-Hill, who has the same coach she's had since she was 13, Toni Minichiello and who married her childhood sweetheart, Andy Hill, a construction site supervisor, in 2013, and still lives in her home city.

"Probably the most surreal moment was crossing the line at the London Olympics. I couldn't believe I'd fulfilled all my childhood dreams and was going to be on that winner's podium. I feel very privileged."

Jessica Ennis is supporting P&G's nappy brand Pampers 'Little Champions' campaign and is an ambassador, along with her mum Alison Powell, for P&G's Thank You Mum campaign. Visit youtube.com/watch?v=OaXcxcmZn5s to find out more.