I don't think he's chubby just needs a little more muscle. Especially the front end. I would do lots of trotting preferrably up and down hill if possible
It's actually not possible at the moment, but I will when he goes back into work. He's been off for a while due to lymes and we are just starting to get him back into work, which he hasn't been too happy about.
I'll start doing that when he is a little less crazy undersaddle.