There are many different excercises you and your horse can do at home. It depends what your into whether it's dressage or jumping there are excercises that can be fun and interesting for both you and your horse.

Here's a few that me & more horse do, to make flat work more interesting : leg yield, shoulder in, about turn, demi-pirouette, loop back to the track, three loop serpentine, turn on the forehand, flying changes, etc.

If you want to know anything other exercises feel free to let me know, hope you found this helpful :)