OK. Just saw the part about not being outdoorsy. Although the dog would be the perfect excuse for getting outside at a nature center or just around the neighborhood or to a park.
Some of my suggestions would still work, but what about things like taking apart old (safe) appliances? Tye-dying t-shirts? Buying actual large canvases and oil paints? Learning juggling or magic or just goofing off with ball and cards? Growing your own summer vegetables and fruit? Going through your old books and toys and going to a donation center? A movie day where they concoct their own treat?
