He is self coached, he relies on YouTube videos to hone his technique -- and in running-mad Kenya, he had to plead with officials to win selection for the track and field team as a javelin thrower.

Julius Yego may not have won a medal at the 2012 London Olympics but his achievement in just qualifying and then reaching the final in this specialist discipline was a triumph over adversity.

"I do not have a coach, my motivation comes from within. Training without a coach is not an easy thing," he told CNN's Human to Hero series.

But this obvious handicap did not prevent him hurling the 800-gram spear 81.81 meters -- his personal best, breaking his own national record -- in qualifying in London to join his sport's elite.

Yego eventually finished 12th in the final behind Keshorn Walcott of Trinidad and Tobago, who shocked the likes of two-time defending champion Andreas Thorkildsen of Norway to win a surprise gold.

Walcott's upset victory, only the second by a non-European in Olympic javelin competition, should act as encouragement to Yego, who is not short of self belief.

"I want to be a legend and leave a legacy," he said.

"My focus now is on the 2013 World Championships in Moscow. I am trying to be in the top three. I have to move into the medal bracket, not just in the finals."

Yego had to battle "a lot of challenges" to gain acceptance in his own country as a world-class athlete.

The 23-year-old hails from a village in the Rift Valley, the traditional breeding ground for the seemingly endless stream of Kenyan distance runners who have enjoyed such success in distances from 800 meters to the marathon.