Fox was taken to hospital earlier this month after feeling dizzy and light-headed during a round of golf, and two days later underwent surgery to replace his aortic valve.
The 58-year-old thanked the fans and the organisation for their concern over the incident and reassured them that he is recovering well.
"I feel good. [I want to thank] all the fans out there, obviously the Broncos organization to allow me this time to get my health back, and the process is going very well, and first and foremost my wife, Robin," Fox told reporters.
"I can just tell you I'm working very hard to get better and my doctors are pleased I've improved every day. Things are going great and they like where I'm at right now."