The Portugal international admits he wasn't at his best last season due to injury.
Carvalho told chelseafc.com: "I am doing good.
"After last year I have been working hard and I am feeling fit, I'm happy to be helping the team again which is important. Sometimes when we had too many games they wanted to rest me, but I want to play every game, that's when I am happy, but I understand that they want to monitor it and manage it.
"I am feeling okay though, physically I am strong and not worried. Last year I was not fit and in that time I had some problems but when I feel fit like now there are no worries."