One of my favourite obedience exercises (that conveniently fosters impulse control and ties into send outs!) is the seek back, where you (the handler) drop an item while heeling and then send your dog back to retrieve it after a certain distance.
(The video is just to illustrate, I don't usually play this game indoors because I need more space.)
In competition obedience, the item you drop will be a leather or cotton glove. In gundog training, you would usually use a dead bird, a bumper, or sometimes a tennis ball depending on the dog. I'm using a holee-roller stuffed with rabbit hide strips because I was working outside earlier and that's my current outdoor toy.
(As always, if you're working on this and its a new game for your dog, be willing to accept sloppy heeling or retrieves at first. You can tighten those things up after your dog understands the idea of the game. You can see Rory doesn't actually retrieve the ball in this clip - this is fine!! I'll fix that later!!)
To start, your dog needs an understanding of heel position and heel movement. You need an item or snack that's valuable enough to be interesting but not so valuable that your dog won't be successful.
Get your dog in heel position and calmly drop a kibble or toy behind you. If your dog is in heel on your left, use your right hand. Do this as boring as possible but make sure your dog knows it's happening. Immediately reward your dog for staying in heel, reward position should be wherever you usually reward for heel (so I reward near my knee). Use a tab leash if you need more clarity or control. Take one step in the direction you're facing. Send your dog to get the snack or toy.
If your dog doesn't know how to bring items back, just use snacks! If your dog usually retrieves really well but stops bringing the item back, they're probably done with this game for now! It's a tricky one so take a break and come back to it later.
Once you can drop your item from a stationary heel and your dog is steady, you can start taking two or three steps in the direction you're already facing. Make sure your dog is in heel position before you send them back to the item. At this stage, send them back to the item while they're moving forward with you - don't ask for a sit or stand yet!
Once that's pretty easy and you incrementally make your way to 10 or 15 steps, you can start adding pauses (sit or stand) or direction changes. Make sure to increase your difficulty slowly so it isn't too frustrating. This is a hard game for your dog!
Once you've got all those pieces, you can start doing this in bigger spaces and sending your dog from incrementally further away! Start on flat ground with items that stand out so your dog can visually find them easily, and then add in difficulty by using terrain or smaller items.
(This is where you could tie in to gundog send-outs - use a bumper or bird, drop it surreptitiously while heeling in a straight line, and then send your dog in a straight line. Slowly reduce the visibility of your item but keep the straight line so your dog trusts your directions.)
I used to play this game with Mav and I would sneaky-drop my keys and send him back to find them while we were walking in the park. I'm using it to work on Rory's heeling, but I love how it fosters such good skills for real life (like say the ones you would need to walk away from a porcupine). As a bonus, it's legit exhausting once you get to bigger distances because you combine the brain work with running very very fast to get the item!