H.W.
I get 'down' around the gray time of year, or on a stretch of gray days. It's a challenge.
Some things that really help:
Get out for walks. Every day, rain or shine. Buy a raincoat and boots for yourself, buy the kids raincoat/rainpants/boots and get out. It's totally worth it. Portland is pretty even on a rainy day, and if you can get out to a more natural setting like a forested or treed park, even better.
Keep a routine. It's easy to just want to 'do nothing' on those grayest of days. Having a routine to stick with--and deciding to be disciplined about it-- helps.
Good music. On rainy days, I try to make the mood warm and cozy, a little bebop for me feels good. So does a cup of tea. I sometimes build a fire, and it gives my day purpose, so that I'm mindful of the woodstove. The dry heat also keeps the damp off our old house as well as my middle-aged bones.
Plan outings, both with kiddo(s) and for the adults. Having a place to go to during the day is good. If you have no place you really want to go, walk to the local bus stop and take a ride somewhere. The kids will love the undivided attention and you'll get to show them interesting things. My son *loves loves loves* taking the bus places and now notices the different aspects of the route.
The adult part of it: get a babysitter every so often (at least once a month if you can afford it, or try to arrange trades with other couples with kids). We have found that an afternoon out works better in most cases than an evening--people are more likely to want to do playdate swaps in the afternoon than evening, and you still get some time together.
Get out on your own, too. Out for a haircut, a cup of coffee, just shopping. Meet a friend a couple times a month for an evening out. It's worth it.
Maybe read a book with a friend, so you have something besides parenting to focus on and discuss. (Good to do with your child-free friends.)
Eat lightly and more healthily than you might normally. I know it's the time to crave carbs, and it happens to me too, but the heavier diet seems to exacerbate the entropy, if you catch my drift.
Find time every day to relax. I'm not even going to say "do one thing for yourself" because for half of us, it's probably getting the laundry folded just so we don't have to see it tomorrow. I'm talking about relaxing, if at all possible. When you turn on the tv, consider eschewing the heavy-duty intense suspense shows and finding something that makes you laugh.
If that all doesn't work, sell the house and move to San Diego.:) My dad did that...only he moved to Santa Rosa, then central Oregon. He was sick of his SADD.