I understand your concern--children can be affected by growing up with a chronic complainer. The first step is for your wife to recognize she is indeed a chronic complainer--but that is not an easy step by any means.
I discuss chronic complainers at greater length in my book The Squeaky Wheel (Chapter 4) and perhaps reading those sections would help her recognize her over-complaining. I also discuss how over-complaining can impact the entire family and I illustrate these concerns with a case study which I refer back to in later chapters (the Bell family).
Perhaps one way you can work on not procrastinating is to take action on the issue of your wife's over-complaining, either by talking to her about how troubled you are by it or by getting her to read the book--or reading it together. You might consider saying something like, "I think we tend to complain too much so I got us a book we can read together" as the 'we' might be less offensive to her than you telling her she's a chronic complainer and has to do something about it.
Also in Chapter 6, "Squeaking to Loved Ones" you'll find tips on how to bring up the issue with her.
Good luck!