I didn't want to have any regrets and be one of those blokes who stands in a pub saying 'that could have been me'
The loose forward has captained Leeds Rhinos through the most successful period in their history, leading them to six Grand Final victories, including five in the last six seasons, and three World Club Challenge wins.
The only player to make more than 400 appearances for the Rhinos, Sinfield has scored more points than any other player, not only for his club but in the history of the Super League.
The 32-year-old has done all this as far away from the limelight as his status allows, with minimum fuss and maximum respect from just about everyone involved in the game.
Now, following the retirement of team-mate Jamie Peacock from international rugby, Sinfield has the chance to transfer his talismanic leadership qualities from club to country as England coach Steve McNamara's chosen leader for the autumn series and beyond.
BBC Sport spoke to Sinfield, and figures from his personal and professional life, to find out what has enabled him to be such a success.
"My brother started playing when he was six at Oldham Juniors, which later turned into Waterhead, the local amateur club.
"I can remember his first game. I came home and said that the Under-Nines were short. I asked him if he wanted to play, but he didn't have any football boots, so we had to borrow some from a friend and put newspaper in the front of them because his feet were so small.
"He picked it up very quickly, though, and by the age of seven or eight he was an outstanding player. I was quite small, but my brother was always quite a big lad.
"A lot of Kevin's success comes down to our parents. We were taught to respect other people and be positive. We are a very close family. There's my sister, she's the eldest, myself and my brother. I live next door to him now.
"Kevin is a very family-orientated person and that reflects on the way he conducts himself. He doesn't really stand in the spotlight and very rarely goes out drinking. I like to think he's the Paul Scholes of rugby league. He's a quiet character but very commanding and gets the respect of his fellow players.
"Kevin has always been mature and had a calm manner about him. From the age of 14, he was very much a young man.
"He's won six championship rings now. I think he gave his children two each, my dad got the one he won last year, while he gave me his ring this year. I was really touched.
"For any young person who has aspirations in rugby, he is a perfect role model. I'm very proud of what he has achieved."
"I've seen him grow up from this young kid that you knew was special. I just didn't know quite how special he was going to be. Having worked with him as a player, you see his professionalism. He is always the last one off the training field.
"I progressed to coaching him, but he is one of those that you don't need to coach as such because you know he leads and doesn't cut corners.
"He has a lot of qualities. Obviously one of those is the way he plays the game, but I'd also highlight his honesty. In everything he does, you know he gives 100% and he lives for his profession. He has an important family life but he puts his profession above things and makes sacrifices.
"I remember the year I retired, at the end of the 2006 season. We went to Catalans in Perpignan. Kev had his own room but there was some mix up and I ended up sharing with him.
"After that trip, I went back to Tony Smith, who was coach at the time, and said if ever you need a young lad to room with anyone, then put him in with Kevin so he can see how to behave properly. He was stretching and doing all that kind of stuff. It was great to see that professional side of the game.
"Without a doubt, he is one of the best captains in the Super League era. There is a dynasty that Leeds have built up and Kevin is a massive part of that. I'm not sure that will ever be repeated. What they have achieved is fantastic and they wouldn't have been able to do that without him.
"Hopefully, there will be more accolades coming his way because he is not only a great rugby league player but a great person. What he has done for the game and for people in the north of England is huge. It has been a pleasure to play alongside him and coach him as well."
"Kev is a massive factor in moving Leeds Rhinos forward, what we've done well and the image it portrays. When Jamie Peacock retired from England, I thought there was only one choice to succeed him and I think everybody feels the same.
I can't think of a more inspirational captain in any sport than Kevin Sinfield. His cucumber-cool leadership and immaculate technique during the fiercest of battles is a lesson to anyone in trusting your team-mates, your own ability and your gameplan when pressure breeds panic elsewhere. That he rarely makes a wrong decision on the field makes him the perfect choice as skipper.
"Kev has done a great job for Leeds and he'll continue to do that for England. He is a cool, calm character who speaks sense, not only in training but in tough times in games. He comes up with the right stuff.
"Not only does he speak sense but he leads by example on the pitch. He is a great guy and a knowledgeable guy.
"The whole play-off system shows that big games need big players and there is nobody bigger than Kev for Leeds. He's been doing it for years.
"It is easy to see why they call him 'Sir Kev'. He is a big hit with the fans and I'm sure Kev will be knighted by the end of his rugby career."
"When I first met Kevin, he was at my old amateur club Waterhead. I was made aware of this talented young rugby player who could dictate and dominate a game at such a tender age. At that point, I was in the professional ranks at Wigan and they were very interested in him, along with Warrington, St Helens and Leeds.
"He was 15 when he joined Leeds and 16 when he made his debut at home against Sheffield. From that point on, our lives were intertwined with the Rhinos.
Media playback is not supported on this device
"Kev won't see this as an insult but I think he is the most manufactured player in the game. From that Sunday afternoon in Sheffield in 1997, he has looked at everybody he can to get the information he needs to be in front in every aspect of the game.
"Kev himself would pay tribute to the people at Leeds. Director of rugby Chris Gibson is a big source of inspiration to players and staff at the club and the passion of people like him runs through to the players who have been here a long time.
"In the period Kev came through, the club was going through transition - legends like Gary Schofield and Ellery Hanley had gone and they couldn't afford the likes of Craig Innes and Kevin Iro so they had to find a way of producing their own players and making potential into reality through the right culture. Kevin is now one of the chief endorsers of that.
"I think Kev's leadership style is total loyalty to the company, to the family, to the team and ultimately to his goal of success.
"When he was first made captain, he didn't have the experience he has now but he did have an unrelenting desire to get things right. That rubs off on people. His inspirational way of leading his life has helped elevate this club to what I think is the best in the world.
"On top of all that, he is bags of fun. When he needs to be serious, he is. But when he doesn't, he is like a child playing tricks and jokes on everybody. He is at a stage in his career now that he needs to savour everything and he does that to the fullest."
"The first side I captained was Lancashire Under-10s. Since then, I've captained representative teams all through the juniors. I was English Schools captain at Under-16 and then I didn't really do it until I was made Leeds captain at 22.
"My mum and dad deserve huge credit for where I am today. They've played a huge part with the effort and hours they put in, not just for me but my brother and sister, making us good people and supporting us on the paths we've followed. Now my wife and kids keep me grounded.
"I like to think of myself as an honest bloke and an honest type of player. I know what my qualities and my weaknesses are.
"I'm not going to say I can do what Sam Tomkins or Rangi Chase or Danny McGuire does. I haven't got lightning pace and I'm not going to rip teams apart on my own. But what I can do is get a team around a field and when I've got talent around me I know the best position to give them the ball in.
"Ellery Hanley would be my big inspiration in rugby league. Around the late 1980s and early 1990s, he was the figurehead for British rugby. What he achieved in the game, how he played and how he led his teams left a big mark on me.
"The other influence is Roy Keane. He has had his run-ins with authority, but he was the best at getting the very best out of the people around him. I'd like to think I can do a similar role.
"When I first started out, I was the kind of guy who wanted to give everything my best shot. I didn't want to have any regrets and be one of those blokes who stands in a pub saying 'that could have been me'.
"It is only a short career and I thought I'd make as many sacrifices as I could and see where it takes me. I missed out on some things, but I wouldn't change anything.
"You mellow a bit as you get older and become smarter with your time. I've always felt guilty going on holiday and having down time. But with the amount of games we've played in the last two seasons, I've forced myself to have some rest. It was difficult, but it was probably best I did.
"As long as I'm enjoying it, my standards don't drop and the coach is happy with me, then I'll keep playing. You play your best stuff when you're enjoying yourself and I'm certainly enjoying myself at the moment."
England have finally acknowledged what the city of Leeds has known for the best part of a decade - that Kevin Sinfield is a born leader.