Do yoga. Not that pretty "flow" stuff but the kind where you have to just stay in that damned pose for eternity. I'm not kidding. I let my yoga practice slide the past couple years, and I regret it now that I have a heavy baby who has to be carried everywhere and who currently doesn't like being worn in a sling or hauled around in a car seat. My back is picking up the slack from having weak arms.
Get some WD-40. This I already had, thankfully, but I'm going to start giving it to people at baby showers I think. That plus some carpet cleaner and laundry detergent in bulk.