For years I tried to solve my marital problems by reading books, taking what they advised, and trying to do it on our own. It never worked. It's like saying to a smoker, "Just stop smoking." Of course, that is the cure for smoking, but it is a lot harder than it sounds. So yes, a good part of the cure for our marriage was to stop focusing on the negative, but we both had to be taught how to do it.
When our unhappiness together reached a crisis point and we were about to contact divorce lawyers, someone told me about Retrouvaille. As a last ditch effort, I suggested that we try the weekend. I never imagined that it would be effective. But that one weekend changed our lives. I suggest that you try to get your wife to go to a weekend with you. First they will teach you good communication skills which help every aspect of the marriage, and then they will go on to teach things like looking at the positive.
