How to get smaller/toned thighs.?

I would like some simple excises I can do (anything, but jogging, I have knee problems) to help tone and maybe make my thighs smaller. I want to be able to wear shorter shorts this summer, without feeling self conscious (I'm 5'7 and 128 pounds). I would like to see results fast, but I know it's not realistic and it will take time. Thanks!