Lots of work like people have commented and a good feed balancer, I used NAF 5star and it really improves their overall well-being, coat, and their muscle tone.
Lots of long and low trot work over poles! Also Hill work, cantering out of the saddle would strengthen all across the back and behind the saddle. Hope this helps🙈
Lunging with side reins, hill work, lots of trotting while being round
Interval work on the hills, especially at the trot. Start slow and gradually build up the time you work your horse, and you should see great results!
Lots of hill work at walk and trot downhill and a little canter up. Circles/serpentines as well as transitions throughout them. Trot poles definitely help.
transitions, trot poles, hills
Workouts, sit ups push ups Russian twists anything to do with your core. It weighs for me personally it might depend on you