Olympic champion Anthony Joshua returned to Kings Langley Secondary School yesterday and told the pupils "make the most of your time here because you never know where you could end up".
Joshua joined Kings Langley halfway through year seven after returning to the UK from Nigeria and remained at the school until he completed year 11.
The 24-year-old was an impressive athlete and footballer in his teens but had never stepped foot in the boxing ring when he left the school at 16.
He took up the sport two years later and went on to win the super heavyweight gold medal at the London Olympics in 2012.
Joshua, who has won all six of his professional fights by knock-out, has been widely tipped for superstardom and two weeks ago was involved in one of the biggest nights in British boxing history, as part of the undercard for Carl Froch versus George Groves at Wembley Stadium.
On his return to Kings Langley yesterday, Joshua held a Q&A with around 20 pupils for more than an hour before signing autographs and having pictures taken with lots more pupils and teachers whilst he walked around the school.
Joshua grew up on the Meriden Estate in Garston and is known as Femi by friends and his former teachers, due to one of his middle names being Oluwafemi.
He had lots of advice for the group of teenagers he spoke to.
Joshua said: "The Olympics was like your homework; if you don't study then you won't pass. You must make the most of your time here because you never know where you could end up."
"I'm just a local lad who gave his best and came back with a gold medal," he added.
The heavyweight prospect did recognise: "I should have made the most of my time here but looking back, I wouldn't have changed it. The mistakes made me the person I am. But I am glad I found this school and met all the people here."
Joshua stated the importance of working hard, eating the right types of food and planning for the future, whilst also stressing they need to enjoy their school life.
"If you give everything your best then you can never have any regrets," he told them. "And take advantage of the opportunities you have at this school."
The rottweiler Joshua used to see on his cross country runs during his P.E. lessons has gone and the 6ft 6 boxer's 100m year 9 record of 11.6 seconds was recently broken by Ben Collins, who ran 11.5 to become county champion.
But most of the school remains the same and several of his old teachers spent time talking to their former pupil, whose visit was filmed as part of a documentary on his life.
Joshua, who now lives in Golders Green but visits Watford regularly, said: "It was class catching up with everyone. You spend so many years here, growing up, so it feels like yesterday since I was here. It was good coming back.
"This is where it all starts. These kids are on the journey of life and it all starts here."
There will be more from Joshua in the Watford Observer on Friday.