Rising trot but don't let your bum touch the saddle
these help really well if you work out in a gym
Any ab workout! Running to help stamina, calf & leg strengthening exercises like stairs. Etc! :)
Plank is really helpful for your core and squats can help with leg strength. You can also do yoga type stuff to help with balance. Swimming also builds a lot of the same muscles because unlike running it builds long muscle which is what is used for riding.
Running, boxing, rope skipping and functional training