The 35-year-old says he came back to European football to show that he can still compete in the Champions League after his brief spell in China.
The Ivorian legend left Chelsea for China in the summer of 2012 after lifting European football's premier competition but returned to European football in January this year.
Galatasaray made it to the quarterfinals of last season's tournament and Drogba is eager to show that he can still compete at the top level.
"I was in China and I felt that I still had something to say in European football," the 35-year-old told Tuttosport. "I wasn't finished. I was full of energy and I wanted to defend the title I won with Chelsea. I felt the need to prove myself in the Champions League.
"Age is nothing. It's just a number. Everything depends on your quality, your experience and your physical condition. I feel very good after all these years and I can say that I have improved both technically and mentally."