This week’s guest, marketing guru Seth Godin, has some motivation that’s going to change the way we think about our personal brand. Seth says that the strength of your personal brand — and perhaps even your entire career — hinges on a single question: Do you do what you say you’re going to do? In Mailbag, Jean advises a woman who rents out part of her home and is looking into refinancing her home loan, and where to invest once you’ve maxed out your 401(k).