Glad CM and his whole "dominance theory, etc" was finally poo-poo'd, and yes, CM does use shock collars, ugh - I was trying to bite my tongue. I also believe dogs need jobs, but not necessarily carrying back packs around. I agree that tires them out faster, but it does nothing as far as mentally exhausting them, or making them feel more confident.
I do Nosework classes with mine, have been for about 9 months. If you're not sure what they are, google Canine Nosework - it's a fairly new sport and it's soooo much fun! Honestly, a 20 practice session at home wears them out, and all they're doing is using their nose, searching for an odor (birch, anise, or clove). My girl will be taking her ORT (Odor Recognition Test) in a couple months, and hopefully entered in Nosework Trials soon after.
I also have been teaching them service-type "tricks/jobs", such as picking things up off the floor for me (just to give them something to do). Any dog can do it, and they feel so proud of themselves. Honestly, I've been at home sick the past few days (so they haven't been walked), and I found myself several times asking one of the dogs to hand me something I had dropped on the floor - they were right there to do it, looking quite pleased with themselves (and I rewarded them big time!). We've also been working on learing to bring in the newspaper (cuz I think that's so cute), and one morning it was raining (and I didn't want to go out) - so I sent the dogs -- and they did it!!
I was so proud of them, and they looked so proud of themselves!! Again, paycheck for job well-done!!
You can get really creative around the house and teach useful-type 'tricks' - it will be fun for the dog, it will look cute, and you might even get some benefit from it.
Thinking about a Cavoodle, anything above would apply. In our Nosework classes, there's been everything from a Chihuahua to a Newfie - any dog with a working nose can do Nosework. It's great for building confidence, and they work alone - which means my fear-aggressive dog can do it, also. As far as learning to pick things up and hand them to you - granted, your pup won't be picking up a phone book, but could certainly learn to pick up light objects: pens, paper, remotes, socks, forks, you name it - any number of things, the sky's the limit. One of my dogs now is constantly watching me to see if maybe I want him to do something, he LOVES his jobs. Oh, he is my cupboard and drawer closer extraordinaire (I leave the kitchen ones open on purpose and ask him to "close, please") - that's his job, "close" the cupboards and drawers if I leave them open.
Drawers might be too high, but your pup could certainly learn to close cupboards - it's cute, and just one more thing he learned, and it's my boy's little job.