London 2012: Jessica Ennis embarks on Olympic training

Sheffield athlete Jessica Ennis has embarked on the most important months of her career as she prepares to go for gold at the London Olympics.

In 2009 she became Britain's first world champion in the heptathlon but was knocked back after coming second in the World Championships last summer.

It has meant a new challenge for Ennis and coach Tony Minichello as they embark on an intense training regime.

Ennis said: "It's a massive year for me, it's Olympic year."

Ennis was a junior champion of Britain and Europe in the seven event heptathlon.

In 2009 she trounced her opponents at the World Athletics Championships in Berlin.

But a poor javelin throw led her to losing her world title at last summer's contest in South Korea.

At Sheffield's English Institute of Sport, Ennis and her coach have been working to make the small changes which are crucial between claiming silver or gold.

Mr Minichello explained: "Now in Jess's career there's a diminishing return on how much better she can get so you're just trying to find very small margins of consistency of performance."

He added: "She's actually training like a beast.

"She's put in some right graft and because I've pushed the sessions on a little bit she's working really well."

At the Olympic training camp, Ennis has been working to master the event she has struggled with the most - the javelin.

She has been working with Mick Hill, former Commonwealth, European and World medallist, to perfect power with timing and technique.

During one training session, she put in a promising performance, throwing comfortably over 40m.

Ennis said: "I need to keep practising and practising and drilling and hope that it just comes naturally."

For six days a week for the next several months, this training regime will be Ennis' life with the approach of London 2012.

She said: "You do get used to it and you do kind of look forward to it in a weird kind of way.

"You enjoy the pain of it, you feel better once you've done it."

BBC Olympics Dreams, which goes behind the scenes at Ennis' training camp, is broadcast on Sunday, 22 January at 17:00 GMT on BBC One Yorkshire and nationwide on the iPlayer for seven days thereafter.