Portugal won in France in 2016 and will face Les Bleus in 2021, along with Germany and Hungary.
"I'm as motivated, or more, than I was back in 2004," Ronaldo said in an interview for the Portuguese federation.
"The Portuguese fans can expect the same as always, a team with motivation and ambition.
"We'll have a positive mentality that things will go well. The team and all Portuguese fans must believe things will go well.
"The captain is good. I've been working well alongside my teammates and the coaching staff. We're focused on working well.
"I hope things go as well as possible, now that the preparation work is done. We just need to fine tune a few things.
"Now the ball just needs to start rolling. We want Portugal to start well, with a win against Hungary."