Circles, shortening/ lengthening within a gait, backing up, belly lifts. Always work up to a heavier work load! Don’t overdo it, be aware and listen to your horse when he/she says they’re tired/sore.
Cantering up hills but don’t over work him/her.
Lots of endurance work in the mountains is great.
Hill work certainly helps!
working them more than often, do not overwork though. keep them active!