The former forward is pleased he has proved the critics wrong, while also identifying where he has improved.
The Blues captain has enjoyed a fine season so far, playing every minute of every game, making a mockery of suggestions that he could no longer play every week due to his age.
The defender has been a key component as he lead his side to their first title in five years, and a Capital One Cup victory as well. His performances have led to much acclaim this season, and Zola says he is delighted that Terry has proved his critics wrong.
"I'm glad and I'm not surprised," said Zola.
“John has done fantastically well. He has played every minute, and the quality that he has shown to play every minute this season is incredible. Considering also his age, it is quite remarkable."
Terry has always been one of the Premier League’s top defenders over the years, and is arguably still England’s best despite his retirement.
It is under Mourinho though, that he has always performed the best, being a key player during the Portuguese boss’ first spell in charge and yet again since his return last season.
While many players his age would fail to improve themselves at such a late stage of their career, Zola says that Terry is not like that at all, with his reading of the game in particular something that has gotten better with age.
"He has a great ability to anticipate danger,” he added.
“He reads the game very well and he knows where the ball is going to go beforehand and this is an area where he has improved. Other than that the courage and the determination is the same.”