I trained Thor when he was two. Well, mostly trained.
It's just like training a puppy, except they can hold it longer. Pick a method, be it a crate, xpen, or keep them leashed to you. Put their feeding on a schedule, take them out on a schedule, give great treats and praise for successful potties, try as hard as you can to catch them before a mis-potty. Don't punish after the fact, and get some Nature's Miracle. It can be done!
