The Lions face Australia in the opening Test of the three-match series in Brisbane on Saturday, having endured one defeat in their warm-up matches prior to the clash.
McGeechan, who presented the players with their jerseys on Friday for the opener, revealed that he tried to further inspire the squad when meeting them.
"From now until the final whistle, it needs to be about them, not about me or others," McGeechan wrote in The Telegraph. "This is a big occasion for them, far, far more so than any other Test match. This is the culmination of four years. This is a moment that will define careers and create lifelong memories.
"It was emotional, as it always is when you are talking to a group of Lions, but it was special to see some players again, and meet new ones too. It lasted no more than five minutes. I tried to pass on to them what the Lions jersey means to me. I hope it meant something to them.
"You do not always have to give out jerseys as part of some sort of ceremony. You have to do what feels right. It is as simple as that. But I know that the connection with the past is important, that sense of legacy that gets passed down through the generations."
The Lions face the Wallabies at 11.05am on Saturday.