If he's getting bored with arena work, get him out of the arena and don't focus on anything discipline specific, just good riding - obviously don't let him be boss and decide what you are doing but take the pressure off a bit. Take him trail riding, kick him out to pasture to just be a horse for awhile. Being stalled and only doing arena work will make a horse sour in a hurry. Ben's too big of a sweetie to let him get sour.
Life is like a camera. Focus on what's important, Capture the good times, Develop from the negatives and if things don't work out, Take another shot.