I know some people have mentioned those treat balls, and putting the rabbits pellets in them.
What style cage is he in?
Mine all live in pairs/groups so they get to socialize with one another when i am not around, i have leveled pens so they bounce up and down the different levels of the cage for funa dn excersice.
I also give toilet paper tubes as toys (cheap lol), wire balls with bells, sometimes apple branches, or a phone book. Not everyones interested in those things, and they would rather play with them with me sometimes. So just keep trying new things. Oh, I also got PitStop a stuffed bunny when his first companion passed away. That kept him with some company during the day, he’d groom ‘her’ and everything.

Ditto Andi.
–Each bun has their own idiosyncracies… you have to find out just what type of stimuli he takes to.

You said you’ve given him a cardboard box – was it big enough for him to get inside it? I find that my bunnies are both obsessed with their Maze Haven – they love cardboard boxes that they can get inside, like a cave or a warren.

I make cardboard tubes filled with hay and dried fruit bits. These are fun toys, and you can do the same with a paper bag (lunch style), they can rip it appart and toss it around to get the treats out.

All my buns (but 1) like to be on the highest thing in the room if they can… such ‘cats’ LOL… so a second level even just a small pertch could be a fun thing for him. But then like you said it may mean blocking off one of the doors on your crate.
Tunnels are a favorite, but they arn’t great for inside cages as they take up a lot of room. My MiniLop will spend a whole day inside the Crinkle Tunnel, sleeping and digging LOL.

Try running away from him and see if he chases you. He may do it, since he likes to be around you, and if he does, he will turn and you can chase him back. If he likes the game, you can do that quickly several times back and forth up and down a hall or across a room and it will get him a bit of exercise.

Spockie seemed to be similar in his attitude toward me, and we got our exercise frequently by playing chase. If you can avoid it, try not to chase him first. That might make him feel like prey and not be fun for him.

Some buns are just lazy – he might not be bored, he might be perfectly content to sit around and do nothing. I often say that Otto’s favorite activity is staring into space. He’s become a bit more active since we got Hannah to keep him company, but honestly he’s just a lazy bunny who doesn’t do much. He seems perfectly happy alone, doing nothing, even since we’ve got him a friend. Hannah is very needy of him and is very attached, but he still doesn’t seem to care one way or another.

I just wanted to share a story of a bunny who sounds like yours and is perfectly happy sitting alone and doing nothing.

In terms of being lazy, Eddie is quite content just to do his circuits of the apartment when he’s free and mainly just lays around otherwise. He does dig and chew at boxes, but not a lot or for long periods. And forget about other toys. I tried teasing him with a rolled up piece of paper and he just gave me the “you are weird” look and hopped off. lol Lolli likes digging and ripping up paper towels so I give her a half empty roll to play with. Neither one really plays with actual toys.

I would say if he doesn’t seem to “play” with things now, he won’t do it when he’s alone. (Eddie never did when I had just him for a year.) Just make sure to provide him with something to do and he’ll take advantage if he wants to. Just wanted to add my 2 cents and experience with Eddie. lol

Crinkle cat tunnels are fun with buns. Mine had out grown hers though, lol.

Some bunnies are lazy bums. Mine enjoys exploring her living room, jumping onto the couch, etc.
Sounds like you are letting your bunny out for a good time each day I work also, and can only let my bunny out for 3 hours during the 4 days that I work. On my days off, she is out for longer.

I have a friend who has a Lionhead. He just stares into space and sways his head back and forth. It is quite humorous!

Have you tried cardboard boxes? A diggy box with shredded newspaper? It is soy based so it is safe if your bunny ingests it.

I can vouch for Elrohwen’s idea of a warren – how bout a manmade warren, a tunnel network?  When you work longer hours, maybe by that time you’ll have a pen set up and tunnels are great inside pens, as well as outside of them. A great way to amuse themselves and I’ve never met a bunny who didn’t enjoy exploring tunnels.  Must be the “warren” instinct.  Here’s my bunny Buddie surveying his ‘kingdom” from atop the interchange cube connecting his tunnels. That thing in front of the purple tunnel is his corner litterbox, ignore that.  Both my bunnies love the tunnels, when not perched on top, they would be madly racing through them!  Too fast to capture with my camera. lol

lashkay – where did you get those tunnels? Seriously. Where? I always wanted to get that type of tunnel for mine. I think they would love it but I didn’t think they made any big enough for bunnies. lol

They enjoy the snugglesafe interchange cube that joined the three sections of snugglesafe tunnels (8″ diameter x 30″ long each) almost as much as they enjoy racing through the tunnels! I got them from http://www.SmyleePets.Co.uk You can get cheaper tunnels identical to Smylee’s from Petstore.com in the U.S. Those are the purple ones. Below is the email I got from Mark of Smylee’s

Dear lashkay,
Hi
We deliver anywhere …we are of course very happy to work out a shipping cost when we have an enquirery.
Was it just the interchange (box in the middle) …or did you also want some tunnels?
Regards
MARK

You’re very welcome. I’ve never tried but I think these tunnels fold back flat – they’re like accordions, though you’d probably want to sit on them-flat. lol They’re only $8 ea. at the petstore place and shipping is only $6 + 1 cent for ea. additional item! Thank you for the compliment on his litterbox. It’s so cute with the one in the picture to watch him plant his front feet through the entrance hole, then swing his butt around sideways to get in, then do an about face with his little head poking out of the hole while his “business” end does business. lol The larger corner box is identical, but big enough for up to a young Flemish Giant probably. I got both on amazon from the same seller, they’re made by Marchioro. The smaller one is 2 cc nora and the larger one is 3 cc nora. I didn’t care for corner litterboxes for the same reasons lots of others don’t, until I discovered these exceptional exceptions. They suit buns’ natural tendency to pee in a corner & the buns LOVE their little hidey hole toilets and so do I, cleaning the Carefresh out is easy and the lid is on a hinge in the back so it just flips up and down. Hurray!

Koji is such a cute name! Have fun, Koji!!

I think I should add this postscript to my earlier suggestion of the plastic rabbit tunnels. In retrospect, I have to say I wouldn’t buy the tunnels for most rabbits. I just the other day made room in Dustor’s pen for the tunnel network and although he had a high old time within minutes accelerating his speed faster and faster through the tunnels, left right and middle, alas, he became obsessed with chewing the edge of the right tunnel. At first, I attached a willow tunnel to the end and he was chewing the willow, but apparently also the plastic one as when I took the tunnels out of his pen, I discovered he had left the edge of the plastic tunnel in tatters. These were said on the site I bought them from to be rabbit-chewproof. Hertofore, I don’t give my bunny ANYthing that’s flexible plastic. Hope this avoids unsafe purchases of this these plastic tunnels. Stick to willow, cardboard, and other edible tunnels.