Here's a thought.
At the weekend I just have to get outside whatever the weather, so the kids don't really have a choice and have to tag along (especially when your wife is gallavanting over to America for a week). Sometimes they are as keen as me but not always and there can be lengthy standoffs as we set off on the latest adventure. There is one sure way to get a smile back on the face of a grumpy daughter and that is to find a big muddy puddle and make a mud stew. Don't get carried away with the role play though, it doesn't taste great.
We found another of those sofa trees that featured in an earlier post.