The Portuguese coach won one FA Cup and two Premier League titles during three years in charge of the Blues, before leaving by mutual consent in September 2007.
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"I think I am better now because my job is the kind of job where experience means a lot," he told reporters. "After Chelsea I went around Europe and had two years in Italy, three years in Spain, so I have more football culture than I did before.
"So I think I am in better condition than before. Some more white hairs, in my case, is a good sign, because it shows I learn more.
"Until the first defeat comes, I am happy. But it is up to my team to help me, support me and try to get good results for the club."
Mourinho, who was speaking in Bangkok at the start of the club's pre-season tour of Asia, also spoke of his admiration for new signing Andre Schurrle, who was close to signing for Chelsea when he returned in June.
"I think with Andre [Schurrle], everybody knows the club was following him for a long time even before I joined," he added.
"When I was faced with the situation that Andre was not far from being a Chelsea player I gave it the last push because he's a player I like who can play in many tactical systems and has qualities that the modern game demands. He is quick, creative and I am very pleased."