By Nick Mulvenney

BEIJING, Aug 13 (Reuters) - Jamaican Usain Bolt has buried his reputation for laziness over a couple of sensational years in which he has become one of the world's best 200 metres runners and set a new 100m world record.

The 21-year-old, a favourite for both sprints at the Beijing Olympics, readily admits that there was a period when his love of a good time meant he was not making the most of his undoubted athletic talent.

"When you're young all you think about is enjoyment, you don't really worry about what the future holds ... being a youth," he said.