What are some good ways to keep my indoor cat healthy & active?

I feel my poor cat is cooped up all day without much exercise. Does anyone have any suggestions on making her more playful and active? She's 1.5 years old.

You can buy/build a cat tree for her, or build a small playground area in one room. Another idea is to be sure your yard is fenced, and go out with her. There are several types of cat fences and enclosures, so the possibilities are limitless.

I have three all indoor cats...I have a cat tree, lots of toys, catnip, a bunch of boxes with holes cut in them, paper bags (not plastic), wheat grass in pots for them to chew on, multiple sleeping areas (with big pillows/blankets)etc. I try to re-arrange stuff every so often to give them new scenery. Oh, I also have a laser pointer...turn off the lights and point it around the apartment...my youngest cat freaks out. It's hysterical. You could also get a second kitten so she has a play buddy.

Bring in catnip. It always gets a cat wild and run around. Give her lots of toys to play with. You could also get another cat to keep her company and to play with.