I have to say that it was with some interest, and no little shiver down my spine, that I read Brendan Rodger’s comments about the current batch of Celtic players and the expectations when they return to the club for the start of pre-season.

Two and a half kilos overweight and away you go to train with the kids until you get it off.

First things first. I got away with murder with some of the managers that I worked under. I’ll be honest about that. When I was at Celtic, Martin O’Neill told the physios that I was to be weighed first thing on a Monday and again on a Friday. I used to tell the physios myself what my ‘weight’ was, once I’d knocked a few pounds off. I’d tell them and they’d scribble it down on a note to the gaffer and that would be that.

Read more: John Hartson: Trust Brendan Rodgers to deliver the right players this summer​

Martin was old school. He knew if he got me to a certain level of fitness I’d get 25 goals every season for him and so we’d a wee bit of give and take there.

I’ll be honest with another one. Gordon Strachan was more in Brendan’s mould. He was keen to embrace the sports science element and we wore the heart monitors and all the rest of it although to be fair to Gordon, like Martin, he knew that as long as I could get about the pitch I’d get the goals for him.

But I remember one day walking through the front doors at Celtic for one of the opening days of pre-season training, whistling away to myself and in a fine mood. And then I heard that they’d set the bleep tests up. My heart sank.

So by the time I got to the dressing room I’d a bit of a limp. I hobbled into the physio with a really tight hamstring – no point in aggravating it before the season had started, was there? And so I got a wee rub down and skipped the bleep test.

Then, one unsuspecting day about six weeks later there I am, sauntering out to training when I spy the cones set up in the far corner of the training pitch. The music box for the bleep test is there. Waiting. And I know, I just know. Gordon put his arm around me. “Right, big man, off you go now….you’re the only one who’s missed it.”

Read more: John McGinn keen on Celtic move as more negotiations expected

You think you’re getting one over a manager but you never really do.

Every manager I worked with was different but they all gave me a bit of wiggle room because they knew I’d score goals. And I knew I’d score goals and I knew how to economise my movement. I don’t know that nowadays you’d get away with that.

Harry Redknapp and I used to go to the dogs every Thursday night because we both had greyhounds. You just can’t imagine that kind if relationship now between a manager and a player.

And I’ll be honest, I don’t look back with any regrets about my career. I had a great time at every club I was at, I love the goals I scored and I had a fabulous career. But I do look back and think what it would have been like if I had been a stone lighter. What else could I have brought to my game if I played under a manager like Brendan who is an absolute stickler for fitness? He demands a certain level no matter who you are or what else you bring and that ruthlessness is what makes him so successful. Any player that plays for him needs to adhere to that strict code. You need to work your backside off for him but he gets the best out of you in return.

And I do think to myself that if I had that little bit more discipline, if I knew I simply had to keep the weight off I think I probably could have gone to another level again. I’ll never know and I don’t have any regrets about my career because I had some super times but you do wonder if you could have pushed it another bit.

And for these players now, what they are been given is every possible chance. It is just up to them to take it.

Read more: John Hartson: Trust Brendan Rodgers to deliver the right players this summer​

I hated pre-season as a player, largely because I always felt that I just wasn’t built for running. I remember at Luton and at Arsenal back when you had five or six weeks off and I could easily put on up to stone in that time. Then I’d go back and work my backside off to get it off for the first game of the season.

It’s totally different now.

For a start, I know at Celtic they are out working with the ball right away. I hear pre-season and I think of being lapped by the goalkeeper as I struggled on a cross country run. God, I remember being lapped once by the goalkeeper, and then by the goalkeeping coach and then by manager! I remember thinking to myself one godforsaken day early in my career that this wasn’t for me. Toiling to get up a hill, breathing hard, trailing miles behind everyone…it was hellish. It was only when they got the ball out I relaxed a bit.

I always knew where the goal was, thankfully.