The football icon has enjoyed a glittering club career but feels that leading his nation to their first major title had more significance - even though he was forced off during the final because of injury.
Ronaldo said: "The start of the UEFA European Football Championship 2016 was going well for me but then I was sad because I got injured [in the final vs France],"
"By the end of the match I was crying with happiness! I experienced three types of feelings and emotions in that game, but at the end of the day it was unbelievable what I felt!
"It is probably the most important trophy that I’ve won in my life."
Portugal will defend their title at the delayed finals that begin next week and Ronaldo feels his country are capable of replicating their triumph of five years ago.
The Juventus forward said: "It was very emotional. To win it again would be incredible, and of course, we go to the tournament with that as our ambition.
"We have a good team but also we know there are a lot of very strong teams there."
Ronaldo also discussed the favourite goal of his career and pinpointed his acrobatic strike for Real Madrid against Juve in the Champions League in 2018.
He explained: "As you know, I have scored 777 goals in my career. It is a bit unlucky but unfortunately, I have to mention that I scored my favourite ever goal against my current team, Juventus, and past my great friend Gianluigi Buffon!
"I would say that is my best and favourite goal that I’ve ever scored in my career."