The England left-back turned 30 in December.
"When I look back, it's crazy to be 30, but I've been playing regularly for 10 or 11 years now," he told chelseafc.com. 'I don't feel 30, we train with a lot of young players and they make you feel young, and I feel good.
"I feel healthy, fit, so as I've said before I hope to keep going for a few more years. It's hard to say how long, I do have a bad ankle and it's not something which just goes away so I have to manage it and take it season by season, but if I look now and say how I feel I know I've definitely got three years."