I disagree with this one. It's possible to live too close to work. If the commute is less than 15 minutes or so, or perhaps more to the point, if it isn't far enough to feel like a separate place, I'm less happy. I need the separation.
I've experienced this both in college — I was happier when I moved across the river from most of my classes and classmates — and recently at a job, where it was about a 7 minute bike ride to work. You'd think that's ideal, but I felt trapped, like my home was nothing but an extension of the office.
One of my happiest times, in fact, was when I had an 11 mile bike commute (or an hour and 15 minutes on two trains). It wasn't very practical, and was logistically difficult (and I was often late), but I felt amazing.
I've never owned a car, though, so maybe the guideline about shorter commutes is correct if you drive. I've always either walked, biked (exercise) or taken the train (opportunity to read, meditate, relax).