The movie star went public with his health crisis recently and revealed he has stage four throat cancer during an appearance on The Late Show with David Letterman in America last week (ends03Sep10).
Despite the diagnosis, the Wall Street star is determined to beat the disease.
He tells Parade magazine, "Life is not all ha-ha-ha, but I'm in good spirits. I'm an optimistic guy. Nothing has deterred me from my belief that I am going to beat this. My doctors' prognosis is for a full recovery (and) I have no reason to doubt them."
Douglas admits he briefly considered keeping his cancer battle secret - but quickly realised there was no way the public would not find out.
He adds, "Not going public with having cancer was not much of an option, even if I had objected. When you are a celebrity, nothing remains secret for very long.
"If it helps bring attention, then that is a major upside to this whole thing. Millions of families are going through the same thing my family and I are now going through. If I can bring any relief or encouragement, that's the good news."