I think it's worse from inside a house. It's like houses are constructed to amplify the dismal feelings about rain. When I get outside I usually find it's very light and intermittent. Like I can actually dodge clouds and peak rain.

Same, I feel very unmotivated to get dressed and going out to commute in the rain, but once on the bike the rainy commutes often are the best!

Make sure to get good rain gear and always have it packed and ready to go to minimize those negative feelings before getting on the saddle.