The 41-year-old guided the Bhoys to the last 16 of last year's competition with a glorious run which included a famous victory over Barcelona. However, as he starts the process of reinforcing his side to do battle on the domestic and European fronts once again, he knows there are important lessons ahead for him.
"You never stop learning. You could speak to Sir Alex [Ferguson] tomorrow and he would say, 'Did I learn it all? Probably not'," Lennon said.
"You all make mistakes - even guys who have been in the game for 20-odd years make mistakes, so you never stop learning. I have plenty to learn - whether I do it at Celtic or I do it elsewhere, who knows?"
Whether Lennon's future lies away from Parkhead remains a topic for debate with the former Northern Ireland international having been linked with the vacant post at Everton, where Roberto Martinez is expected to be installed.
However, while he admits the rumours are flattering, he insists he has had no offers to ply his trade elsewhere and is perfectly happy where he is.
Lennon said: "I have had no offers. It's just speculation. It's nice to be linked with these things, but you take it all with a pinch of salt. It's just rumour, speculation.
"I love what I do. The size of Celtic sometimes gets under-estimated, not by people here, but by people elsewhere.
"You saw Celtic in all it's glory last season with the Champions League run that we had and the supporters, the way they behave impeccably, not just at home but away from home as well. They turned the games into a carnival atmosphere.
"The players we have got, we have got a very good young side who have performed very, very well at a high level, and it augurs well for the future."