Yeah, you probably won't get nominated for saint of the month... but the stress point is valid, at least for candida. No combination of strictly no-no products in any quantity is as likely to set those bloody fungi off, hard, than a good bit of stress.
Personally, I wouldn't expect not smoking to be that major a stress factor for me - it's more of a matter of "is ANYTHING allowed with this?!" and the stress factor surrounding the realization that a medical condition is wholly dictating every damn step in your life.