We've all made mistakes and we all have regrets. Those misdemeanours, though, rarely end up costing in excess of £7m.

Then again, there are not may of us who are in the type of employment that would allow such funds to be earned, unlike footballers - just ask Keith Gillespie.

On the face of it, the Northern Irishman was a talented winger who had graduated as part of the 'Class of 92' along with the likes of David Beckham, Paul Scholes and Gary Neville at Manchester United, before being sold to Newcastle United in 1995 as part of the deal that took Andy Cole to Old Trafford.

He'd go on to excel at St James' Park with a string of top-class performances - the most memorable of which saw him twist Spain international full-back Sergi one way and then the other as the Magpies recorded a 3-2 victory over Barcelona on Tyneside in September 1997.

All the while, though, Gillespie was harbouring a secret. Many knew of his liking for a flutter, but the level in which he was doing so was unknown. However, in what is a forensic autobiography - titled 'How Not To Be A Football Millionaire' - the now 38-year-old has revealed that the majority of his £7,215,875 earnings ended up in the bank of bookmakers.

"I've got an addictive personality, so I was always going to get the buzz from betting. The boredom side of things really hit me hard when I joined Newcastle. It was around my 20th birthday and I was living in a hotel for five months," he told Sports Mole.

"I was done with training around 12.30pm every day and I was going back to an empty hotel room and I didn't really know anybody. A lot of the players have got wives or families to go home to, whereas I didn't. My afternoons were spent in the bookies to relieve the boredom."

One chapter in the brutally honest book, named 'Black Friday', tells a story of one Friday in October 1995 when Gillespie started to bet via a bookmaker over the telephone. Several losses later, he was £47,000 out of pocket and needed his manager, Kevin Keegan, and the club to help drag him out of the mire.

"To me it is the only way to write an autobiography. I wanted the credibility because people and supporters would be reading it. It's took me over two years to write it and I'm glad people can see how my life has developed," said the former Northern Ireland international.

"It was quite therapeutic at times. It wasn't difficult because these things have happened to me and I feel that I have a great story to share. I'm just telling my story – both from a long a time ago and some recent bits. Gambling is an addiction that does grab hold of you and it is very hard to get out of it.

"The feedback that I have had, a lot of people can't put it down and that's what I wanted. You want to captivate the reader and I hope I've done that. There's a lot of stuff in there will take some people aback, but for me it is like a type of closure. There are no secrets – it's all out there. People can make their own mind up on it."

Gillespie is only too aware that he was not the first and certainly will not be the last professional footballer to squander eye-watering figures to the bookies.

In 2009 it was revealed that current Stoke City wideman Matthew Etherington had run up debts of £800,000 after betting £40,000 a month on greyhounds, horse racing and poker. The likes of Paul Merson, Michael Chopra and Dietmar Hamann are also known to have lost big sums of money.

"Gambling is rife in football, without a doubt. You only have to look at the television. When the half-time whistle goes, the first thing you see is a betting advertisement. Gambling has been involved in the game for a long time. There will be plenty of players betting as heavily as I did, maybe even greater," claimed Gillespie.

"As the years have gone on, more money has become available to players – more than you can ever imagine. The thing is, whatever they bet, they know that they will have a wage coming in at the end of the week. Footballers, as I proved, can be quite foolish with their money."

Former Professional Footballers' Association chairman Clark Carlisle, who himself has previously admitted to high amounts of gambling, recently revealed that talks had taken place about banning their members from placing a bet.

While Gillespie doubts that the PFA could enforce such a rule, he does believe that they have a key role to play in helping those who are addicted.

"The PFA have got a lot of people in their union, but they can't follow every player and I'm not sure they can [stop players from betting]. If the player were to go and seek help, the PFA, I'm sure, would be absolutely fantastic. They are a great union. The PFA aren't to know what is going on all the time, so until a player is open and honest about it, the PFA cannot put them on the right path. There is nothing they can do until that point," he said.

"I've told my story about how I got involved with it. It's important for young players to get a hobby – I didn't really have one. It sounds simple, but it's vitally important where the boredom is concerned. I don't think players finish as early as we did when I was at United and Newcastle, they seem to be in a lot longer doing more training.

"I feel I've done my bit now by telling my story. There are a lot of people who will want to give you advice, especially about money. Sometimes it's important not to be naive, but I was probably too naive. I had a lot of financial advice and it wasn't good. You've got to have good people close by you to give you good advice.

"It's very difficult for players these days to have a life away from football. I should have found a hobby because it would have kept me out of the bookies and solved the boredom. I suppose the real danger is now that you could still be on a golf course, but you could still be putting a bet on using your mobile phone. It's very difficult to get away from gambling full stop."

You can purchase a copy of Gillespie's autobiography - 'How Not To Be A Football Millionaire' - by copying and pasting this link into your search bar: http://www.mirrorcollection.co.uk/products/details/search_results/keith_gillespie/