There are many different exercises that you can do with your horse.
I recommend that you spend a maximum of 3 days a week jumping your horse. Each session should be no longer than 20 minutes of constant jumping. Afterwards, you should break off and do some dressage/flatwork for 10 or 15 minutes then resume jumping for another 10 minutes before cooling your horse off or going for a short trail ride.
As for different activities. There are loads of different activities you can do. Use your imagination. Or, if that isn't possible, refer to some horse books, or use a search engine to find some.
Courses are always good practise, and striding work is good too.
Whatever you decide to do, remember, don't jump for too long at any one time. Your horse or pony can become bored which can cause it to refuse or run out on jumps that it wouldn't normally do, purely out of boredom.