London, June 2 (IANS) Singer Robbie Williams says he has experienced change after he started injecting himself with a sex hormone twice a week.

The 37-year-old admits he uses testosterone jabs to fight crippling lethargy, reports thesun.co.uk.

"It has changed my life. I feel I'm getting a second wind," said Williams, who took to injections after a doctor told him he had the sex drive of a 100-year-old.

The singer had visited the doctor for some Human Growth Hormone (HGH) - popular with wealthy middle-aged men trying to battle the march of time. He had blood tests in Los Angeles that showed he had extremely low levels of testosterone - a hormone that boosts sex drive.

So, Williams began injecting himself with testosterone twice a week.

"To cut a long story short, I went to get some HGH. It's what all the old fellas are on out there in LA that's making them look 40 instead of 60. It's improving their health, their memory, their hair, skin. Could give you cancer. I weighed that up. Thought I'd have it anyway. Went to see a Hollywood doctor. Had my blood tests. Went back. He said, 'You don't need HGH. You've got the testosterone of a 100-year-old man'. And then everything made sense," he said

Williams has now been injecting himself for two years.