A high school teacher is set to put his endurance to the test to help poorly children once again - this time, not just once but twice.

When Luke Greer completed the 100km run from London to Brighton in aid of the Great Ormond Street Hospital (Gosh) last year, he said it was the hardest thing he had done in his life but that he would do it all again.

True to his word, the 34-year-old has set himself a new challenge; one which he says is 'bigger and better'.

The Reepham High School and College teacher plans to not only complete the London to Brighton 100km (62 miles) run for a second time next month, but also plans to do the Thames Pathway Challenge, another 100km run, on September 13.

He hopes to beat the £9,000 he raised for the London-based children's hospital last year.

Mr Greer, who lives in King's Lynn, said: 'I kept up the running afterwards and I wanted to do something else for Great Ormond Street.

'I couldn't believe how much I raised last year and felt if I was going to raise that kind of money again, then I was going to have to do something bigger than what I did before.'

Mr Greer chose to run in aid of Gosh because of friends and colleagues who have needed services there.

He has been in training since January 1, completing up to 60 miles a week including a 30-mile run at the weekend.

On one of his training runs, he recently ran from his home in King's Lynn to his dad's house in Watton.

Mr Greer is hoping to complete the Action Challenge London to Brighton run on May 24 faster than his time of 14 hours and 15 minutes last year.

He said he decided to do the second 100km run in September, which is organised by the same company, to give himself enough time to recover.

'I'm looking forward to it,' said Mr Greer, who lives with his partner Poppy Finch.

'I will enjoy the route and scenery - it will be a different kind of challenge.

'Last year, six friends came down with me and followed the route to certain checkpoints.

'Those bits gave you something to look forward to, and I really enjoyed the finish line at Brighton race course - and a glass of champagne at the end.'

Mr Greer has so far raised £2,500. To sponsor him, go to www.justgiving.com/Luke-greer.

You can also donate by texting LRGR79 and the amount to 70070, for example LRGR795 to donate £5.

Are you undertaking an extreme challenge for a good cause? Email kate.scotter@archant.co.uk.