If you feel bad that you can’t wear “nice” or “cool” or “professional” shoes at the moment (as you may have been able to do before children), just tell yourself this: it’s much more important to be practical now, during this time of caring for a growing family, than it is to attract attention or be with-it stylistically-speaking. Wear what is comfortable and then forget the rest. Luckily, you married someone who loves you for you, so it doesn’t matter a whole lot if the outside reflects the realities of life right now. (I laughed out-loud when Alicia Florrick from The Good Wife was wearing her tall shoes when they were flashing back to when her kids were young. That is exactly how it is not in real life!) Remember that shoes are a symbol of what you willingly sacrifice for the good of your family (and for the sake of your back).
Along these same lines (sort of), view food as a symbol of discipline (even though your spouse loves you no matter what you look like). Just because food (and other can-be vices) are effective in their short-term comforting abilities, they fall short over the long run. It’s going to be hard to train yourself to not over-indulge in stuff—the over-indulging you may have been able to do before children without suffering too many ill-effects of it. But now that things really matter more than ever (and catch up with you ever so more quickly), choose to live healthily in all areas with a focus on balance (e.g., one cookie won’t hurt you, but all of them will).