Compact home exercise equipment

Hi, I wonder if anybody could offer me some advice about compact home exercise equipment? I am a runner; have been doing a half hour run pretty much every day for over 20 years. However, after a recent injury, I'm afraid to run anymore when it is icy or snowy outside. So for bad weather, I'd love to have some sort of good aerobic workout that I can do in the house. But the problem is, our house is TINY. We have no room for a treadmill or an exercise bike - at least not the typical ones you see. Can anybody suggest some kind of exercise equipment (maybe a rowing machine?) that is either very compact or that is foldable? It also needs to be sturdy (not fall apart after a few uses) and to provide a good workout. Thanks so much in advance!