Any suggestions on new exercise for cats?

Since I saw a coyote in my yard, I decided to keep my cats in (much to my cats' dismay). My sister and I put the dog kennel at the back door, so they have an enclosure which I put carpeted cat seats in, and a ladder to climb on (not near the top of the fence of course!) and a tarp on one side to keep shaded and to keep dry in rain. So everything was great for awhile because they seemed satisfied. But lately I noticed they have so much energy at night, and recently one started hitting the other cat and my dog which she hasn't done in awhile, possibly when I last attempted to keep them in. I think they are not getting enough exercise, so I bought a battery operated squirrel in a ball, a cat dancer, a bird on a string, a bunch of ping pong balls to put in a box or to have them chase around. I've tried so many things, but I can't seem to get this one cat who is acting out to run around. She seems to want to, and in fact tried to chase another cat in the kennel, but it wasn't "play" unfortunately. When she gets exercise, I believe she is in a better mood, and rarely fights with the other cats.
Does anyone have any thoughts on how I can get her to run around, other than letting her out of the enclosure? I feel badly about keeping her locked up, especially when I remember her running freely around the yard, but I rather have her safe and find a new way to exercise. Thanks very much!

One thing you can do is right before you feed them, if it is canned food, put the bowls in different places up high, so they have to work or climb to get to them. If you have an old fishing pole, take one of their lightweight toys and tie it on to the end and go trolling for cats. I have a piece of cord that has a snap on one end, and a toy on the other and it is long enough to drag the ground some distance behind me. When I am cleaning house, I snap this line on to my belt loop and just do my thing. Eventually, I have about 7 cats stalking me as I work (except when I run the vacuum!) Then they scatter! LOL

Hope these tips help!

Hissy - that's fabulous!

I was going to say that it sounds like the only sure way is to find some time to play with her, and the fishing pole (We make our own with dowel rods and string) toys are a sure way to get exercise for everyone.

We live in a confined space, and maybe one of the ways we deal with that might help you. We change the environment every day. We use paper bags, boxes, and tubes. Lots of them, most of them placed in different areas. Bags some days, boxes the next. Boxes with tubes. Different toys in different things. Boxes taped together (with holes cut inside the levels so they can climb around inside, too) to provide different heights. A bag in a box. At the end of a tube. They always have something new to explore and some new way of ambushing each other, using up lots of energy.

Also, we circulate the toys every few days. Then it's almost like they're always getting new toys, and their interest in them gets renewed. That balls in the box - one of our kids' favorites its first day out is the ring with the ball in it. They tire of it after the first day. But if it isn't around for a few days, they love it again.

It might sound like a lot of work, but the only thing that is are the "box-condos."

Hope you find something that helps! It's so dangerous for the kitties out there!