flatwork

I love doing flatwork, and my competition horse does too. It's a huge part of our daily routine! I'd love to know what some of your favourite flatwork exercises are as any time I ask my horsey friends they always recommend something really interesting that I can add to my flatwork routines...

Can anyone recommend non-schooling activities/exercises I can do with my mare? We do a lot of flatwork in the week but I am worried she is going to go stale and get bored doing the same stuff each week. Unfortunately we can not hack. Any recommendations for some fun activities to keep her keen...