Do you happen to have a laser pointer on deck? If you don't these devices are incredibly cheap and can be bought for about $20 or less. When you do get a hold of a laser pointer, then you'll be ready to try this activity out. Most pets love chasing after the red dots laser pointers produce and Ultimate Mastiffs are no exception. You can give your dog a real workout by pointing your laser at a surface and allowing your dog to chase after the dot to their heart's content.
Here's an interesting new twist you can put on an old school activity. The next time you and your dog head out to play fetch, don't wait for your dog to go bring the item you've tossed to you. Instead, race your dog to see which one of you will make it to the object first.