Fox collapsed last month and was forced to undergo aortic valve replacement surgery, which required over four weeks of recovery time at home away from the club.
In his absence, his side went 3-1, with their only defeat coming against the New England Patriots in week 12.
"I feel tremendous," Fox told reporters. "As my surgeon said, I had a valve that was about as big as a pinhead, and now it's about the size of a 50-cent piece.
"I feel tremendous, obviously the doctors feel good about me getting back to work.
"I actually would have preferred to have been back sooner, but there was a pretty hard deadline after the surgery of four weeks, and I honoured that."