He said: "It was a very difficult period. I was still little, I spoke with the Madeira accent and the moment I asked a question people made fun of me.
"It was very hard to leave my family so early, to discover a different culture, a capital city. Lisbon has nothing to do with Madeira.
"Everything was difficult. I missed my parents, my brother and my sister enormously. But that adds value to what I have achieved.
"When I returned home and then had to go to the airport to take the plane back to Lisbon there were tears and more tears. But we knew it was necessary if I wanted to become a great footballer."
One of Ronaldo's darkest moments came when Sporting's youth side went to Madeira to play against the precocious star's local team. The whole town were waiting to watch the pride of Madeira playing with the big-city boys against his childhood pals.
Yet Ronaldo was heartbroken after being dropped for being naughty at school.
He recalled: "That was one of my biggest disappointments.
"We had to play against Maritimo's youth team in the neighbourhood I was born. All my friends and my entire family were waiting for me.
"But the coach punished me because I did something at school, I don't even remember what now. I cried so much. But I learnt to respect people a bit more, coaches and teachers.
"After that things went better and better."