Jessica Ennis begins London 2012 graft

Jessica Ennis says she will punish herself throughout the winter months as she puts in the physical work that she hopes will lead to gold at London 2012.

Heptathlete Ennis - one of Team GB's favourites for athletics gold - says she knows the areas she needs to improve on if she is to realise her ambition of becoming Olympic champion, after having to settle for silver in August's World Championships in Daegu.