Drenthe joined Real Madrid from Feyenoord after featuring at the 2007 Under-21 Euro for the Netherlands.
The 35-year-old, who admitted that he was distracted during his time at Real Madrid and paid the price, was released in 2012 after two disappointing loan spells with Hercules and Everton.
“I was twenty years old and at the peak of my career. It was my dream to walk into the Real Madrid dressing room. I’ll never forget that.
“But you have a life as a footballer and a life as a human being. You can mix that up to a point, but I did not see the need to change my lifestyle right away,” Drenthe told Gazzetta.
“Now I am aware that I didn’t do the right thing, that I made mistakes. I was not ready to be a pro. I thought I was God, loved women and partied too much and you can’t combine that with football.
“I learn something new every time, but what happened, happened.”