FORGIVE your enemies but never forget their names.

So said John F Kennedy, the former US President, who no doubt spent hours scribbling Nikita Khruschev's name into a jotter over and over just to be sure.

His modern-day namesake is more sanguine. If John Kennedy ever thinks about Ionel Ganea and the tackle that marked the beginning of the end of his playing career then he does so with no feeling of ill-will or malice. Kennedy was only 21 years old at the time but his potential was already evident. The previous week he had helped Celtic record a clean sheet against Barcelona in the Nou Camp, and now here he was at Hampden making his international debut against Romania. The crude lunge from Ganea, however, that seriously injured his knee changed everything. Kennedy did not play a competitive match for three years, and would battle on for another two before finally calling it a day. A career that had promised so much was over by the age of 26.

That would be enough for some to harbour lifelong grievances but, instead, Kennedy has chosen to channel his energies in a more positive fashion. Having to quit playing led him to take up coaching a lot earlier than many of his former peers and he believes that has already given him an advantage. "At no time did I think I'd be first-team coach at Celtic by the age of 31," he admits.

Celtic stuck by their former player and tried to find a role for him. For a while he was an ambassadorial figure, and then became involved in scouting. It is in coaching, however, where he has thrived, initially with the club's youth players and development squad and, this season, with the first-team squad alongside manager Ronny Deila. That the Norwegian arrived in Scotland without a backroom team presented an opportunity, and it is one that Kennedy has grasped gratefully. He, Deila and assistant John Collins have just led Celtic to a domestic double in their first season together.

Perhaps - and we're into Sliding Doors territory now - it would have been different had Kennedy not found a new focus in his life, but from his current position he displays no bitterness about the past. There is almost a Zen-like calm about him as he insists he has moved on from the end of his playing days and is now heartily embracing a new challenge. So is he not angry at all about the tackle that ended his career 11 years ago?

"No. It's totally gone, 100%," he said, without a second's hesitation. "Early on I was given the hope of coming back to play and managed to do that for a short period. But as soon as it happened [and he had to retire] I thought, "right, that's it. It's gone".

"There was no point in me wasting energy on a tackle that put me out the game for two years. It is done and dusted and I gave myself the goal of trying to get back fit again. When I got fit again I tried to get back in the first team. From there I set a new target and eventually reached the end. But there is no bitterness there at all.

"It's one of these things that's in the past, it's not something I think about anymore. Even when I speak about it there are no hard feelings towards anyone. I don't regret anything. When I got injured it happened and I gave it everything to get back to where I was. I'm in a new place now, and a new position and that's all I focus on."

Coaching has more than filled the void in his life. He is, unsurprisingly, in no rush to leave the good thing he has at Celtic but will at some point move on to become a manager in his own right.

"My career was cut short but this is an opportunity for me to get a head start on guys who will play until they are 35 and that's exactly what has happened," he added.

"I'm in a position which I didn't expect to be in so soon and I want to build on that. Ronny came in and appointed John and myself after speaking to us. He got a feel for us before making his decision. He thought we were the right people to be beside him. It's worked well, we've got to know each other after realising very quickly we were good together.

"It's certainly a job I'm finding very enjoyable. We all have a stay on team selection and on things going forward. He's very good at listening which is the most important thing because you feel you've got a manager willing to take on board your opinions.

"Further down the line I'd like to be my own man, but there's no rush. I'm in a good place working for good people. You are in an environment where you have to push yourself to get results and perform and there's no better place to perform."