However, the former Leeds Rhinos and England captain has offered an insight into how folk in Leicester, where he recently became Leicester Tigers defence coach, are also supporting him for his latest “brutal” challenge.
Sinfield, who memorably helped raise more than £2.7m for former team-mate Burrow and the MND charity by running seven marathons in seven days last December, will attempt to run 101 miles in 24 hours, starting Monday and finishing the next day.
The route is from Leicester’s Mattioli Woods Welford Road stadium to Headingley Rugby Stadium with Sinfield aiming to raise £100,000 which will be equally split between the MND Association and the appeal to build The Rob Burrow Centre for Motor Neurone Disease in Leeds.
Sinfield was at the School of Sport at Leeds Beckett University’s Headingley campus today undergoing a series of tests ahead of the grueling challenge.
He revealed they had already reached their £100,000 target in sponsorship alone - “that is really special” - while they also have a further £80,000 on top before the 41-year-old even begins the run.
But Sinfield, who won every honour in the game as Leeds’ most decorated captain, spoke about how the rugby union community has also got on board.
“These guys on the vest have all put significant amounts in and then there’s a few more who want to be silent who have given unbelievable amounts,” he said.
“I won’t disclose who but I can tell a little story: I rocked up at the Leicester training ground one day and had a letter with a cheque for 20K from this kind gentleman.
“He left some contact details. I tried calling him several times and couldn’t get hold of him. I finally got hold of him last week and had a conversation with him.
“Just as I was putting the phone down he said ‘hold on a minute, I’ve got another cheque for you. I’ll send it to you in the post.’
“That came through on Monday and it was just short of 13K so one guy has given almost 33 grand which is absolutely incredible.
“It’s someone involved with Leicester. His former business partner died of MND. You just don’t know who’s out there, who’s challenged and affected by the disease.
"Some of the letters and cards we’ve all received have been mind-blowing and inspirational. Leicester have been brilliant. There’s fans down there stopping me and handing me tenners and twenties. It’s really kind.”
The run will be split into 7km sections, to mark Burrow’s iconic shirt number, with each section to be completed within an hour before the next leg starts on the hour.
Due to the scale of the physical exertion, and logistical aspect, Sinfield conceded it is hard to even prepare for such a task.
He said: “Last Monday we did a 12 hour stint as a challenge so that was 52 miles.
“It was tough. Pretty brutal. I think it was important we went there. We have to be prepared to go there. That’s the big message in some of this: Rob’s going through bits now where it’s uncertain and each day he wakes up it’s a little bit worse than the one before.
“He’s not quite sure what the journey is going to be like for him and where it’s going to take him.
“And we’re in the same boat on Monday. Yes, we don’t have MND but we’re going into a pretty dark place, we’re not quite sure what nasty things await us and we’re prepared to go in there.
“He thinks that’s hilarious but, for him and everyone else around the UK challenged by MND in some form or some way, I think to see other people willing to go to those dark places is pretty powerful. We’ll give it our best shot.”
Sinfield was due to visit Burrow - diagnosed almost two years ago - this afternoon following his press duties, something he was especially looking forward to.
Jamie Jones-Buchanan will join him on the challenge and it is hoped fellow former team-mates Jamie Peacock, Danny McGuire and Gareth Ellis will also all take some part. Does it ever cross his mind he might not complete it?
Sinfield said: “Yes. It crossed my mind at the start of October I might not finish London (Marathon). It crossed my mind I might not do Seven in Seven. It crossed my mind when I was sitting in dressing rooms waiting for Grand Finals, I might not be good enough, I might not get there.
“I think self-doubt is part of life and part of being in sport. It’s part of facing challenges. I think my experiences in rugby as a player have given me the best prep’ for this mentally. But absolutely, we all have self-doubt.
“A lot of people don’t want to admit to it but we all have it. What I would say is I’m determined to get it done and if I have to crawl, I will crawl. I’ve got these guys alongside me who know what buttons to press and that’s the beauty of being in a team.”
Donations can be made via https://donate.giveasyoulive.com/fundraising/kevin-sinfields-the-extra-mile-challenge.