The Ivorian centre-back has completed his six-month ban and is now back in training as he attempts to prove he is good enough to get back into Roberto Mancini's team.
The 30-year-old took what he thought were diet pills but was given the suspension when the pills were revealed to be bendroflumethiazide - which appears on the list of drugs which are banned by the FA.
The ex-Arsenal man told City TV: "I feel 24, 25 years old. I want to show all the people that think Kolo Toure needed tablets, water tablets, to be a better footballer. I just want to show them and that’s what I will do.
"I will give 100 percent in every single game to show those people I don’t need water tablets to be a strong man. I’ve been in this league for almost 10 years now, being unbeatable with Arsenal, doing a lot of good games. I just want to show them."
Toure remained upbeat during his ban even though he wasn’t allowed to train with the rest of the squad until last month and revealed that he is eager to reboot his career at City: "Sometimes when you come every day to training you can’t realise how big it is to be a footballer.
"I just realised how much we are lucky to be footballers and be able to play for a football team like City.
"To be able to come back and train with the team, come into the training ground, it’s great."