What can I do to keep him busy?

It sounds like you’ve tried a lot of options. I recall trying to think of activities my cousin would enjoy when she went into Memory Care. It was quite similar to what you describe. I’d provide her CDs, but she wouldn’t play them. A tv, she forgot to turn it on. Magazines….she had no interest in reading. A fidget board….she ignored it. She might participate in a group activity if she had direct supervision for a limited time. Otherwise, she just wheeled herself around in her wheelchair. She held her dolls sometimes, but that’s about it.

As I read about dementia, I learned to not think of things that I might enjoy doing, but a person with dementia. They may be fine not engaging in games, activities, etc. they may not have the ability to engage, though they say they want to.

Some people enjoy folding clothes, listening to music or watching fish in an aquarium. Good luck on finding some solutions.

I agree with @celia16 on the ideas she mentioned. It might help to think of your/his day like they do in early learning centers. Each block of time has a focus. Then when he says, what should I do, you can direct him to go to the “center” activity. Even if he just sits and ruminates during that time.
Things like:
It’s house work time!
Folding laundry (he may not notice that he folded all those same towels, or the stack of washcloths, or pillowcases, two days ago) Keep a laundry basket with stuff ready. Or, Empty the dishwasher (onto the counter?) Or, Dry mop the floor.
It’s outdoor time!
Clean your tools, wipe them down. Maybe there are lots of tools? Maybe he re-cleans them. Or, Sweep the walkway. Or, sit in the shade/sun. Or, wipe down the car with a soft cloth.
It’s music time!
Can he remember how to use a boom box or record player (tasks from the past or usually easier to recall how to do).
It’s “reading” time!
Will he flip through sports and automotive magazines that have lots of photos? Can you ask family or friends to create photo books (simple, in plastic sleeves) of them, him, sport hero’s, blast from the past pics. He may look through these over and over.
It’s video time!
If you can afford a tablet (iPad, or android) you can make only the apps you want available to click on. Then put a variety, but not too many, on the main screen - one for sports news, a channel for sporting events, one that might only play old sitcoms, a YouTube channel for bloopers, and one for a fix-it guy. After a bit you might figure out which ones he uses most and find similar stuff. You would want to hide the settings app, use parental controls to limit purchases. A high schooler (friend’s kid, church) could do a better job than I would setting this up.
There is probably a way to create a YouTube channel of your own that he could view on the TV, not sure how to lock out all the other channels but there probably is a way to do it. Your YouTube channel could be limited to subscriptions to the same type things I mentioned for the tablet.

How about taking pictures outdoors, or birdwatching and then identifying the birds. Can he help with vacuuming or something? What if you put a jigsaw puzzle right in front of him, would he work on it? Audio books? Pulling weeds? Clean out the garage or basement or sweep the floors. Models of planes or maybe dinosaurs for grandchildren? You can buy kits to build birdhouses and then paint them. Or set up an easel and paper and he could paint? If he can remember the past he could write his life's story for family. If the "executive" function of his brain has been damaged he won't have the impetus to get up and do things so you have to get him started because he can't get himself started. Turn on a movie and maybe he'll watch it. Don't wait for him to make a choice - make it for him. Can the two of you go to the park or something? Or Zoo? Can he pull weeds? I've found that if I ask my husband to do something for me, he usually will, like feed the dog. And if a time deadline is associated with the task, so much the better. Can he start the coffee in the morning? If he takes naps, have him do something then he can nap. Maybe get up, make coffee, eat breakfast, watch news and let you know what is going on in the world, then do an activity, lunch and then a nap, then maybe help you with housework or yard work or do another activity, watch news before dinner, help you make dinner or visit with you while you make it, eat dinner, go for a walk, watch some TV, go to bed. Or something like that. If you have a dog it could be his job to play outside with the dog. Just blurting out some things that came to mind. You have to take the lead and get him started. Best of luck.

@gpingley477
Since he liked sports and gardening, find stations/programs and documentaries that play regularly for him to watch without needing to find them himself. You may need to do some searching/digging.

You can get albums/pictures loaded onto a USB and have them play continuously on a laptop, smart tv or digital picture frame. This way, the pictures rotate regularly and you can talk about them together when you come into the room.

Can he go with you for walks? Do you have a dog or cat he can interact with?

Can you play music he used to like listening to in the background?

@gpingley477
How long has your husband had dementia? Does he have a specific diagnosis? My husband was a movie buff, so he loved watching movies. However, as his Lewy Body dementia got worse, he no longer could follow a plot or know when a show ended. Music is the only thing that soothes him when he is agitated. Our loved ones will go through stages where the "interests" will change. I like all the ideas here. But keep in mind that decision making is out of their hands now. Make the decisions for him. When he says, "What should I do?", respond with "Well, today I thought we would _________. How does that sound?" You may go for a walk, work in the yard, or go for a drive. We are now almost 6 years into our journey, and I am not only his wife, caregiver, and financier; but I am also his Entertainment Committee! Good luck to you and your husband on this journey.

These are all great ideas. I've been struggling to keep my DH entertained and engaged and you've got me thinking about options I hadn't thought of. Thank you !

Thank you. This is very helpful. He was diagnostic 3 years ago with diffused dementia, but exhibited behaviors at least 3 years before that. I gave up his phone because he couldn’t remember how to use it at all. I could kick myself now because all of the music he loved was on it. I am working to try and see if I can recover it, but I doubt if I can. The music is the piece I really want to get a handle on now. I use many of the others and work hard at scheduling, but my nature is to do to things as I think of them. Still struggle with his early morning confusion and sundowning.

So many good ideas. We are in an independent living facility so many of these are done by others. We go somewhere & do something most days. I guess the biggest problem is after dinner during the sundowner period and also early morning.

Good ideas and I have access to these. Now I need to get organized and make them easily available.

I have a similar situation. My husband used to ski, hike, go on long bicycle rides with a bike club, and now is envious of my activities (I visit the hospital with my therapy dog etc). He doesn’t have close friends in the area…fortunately can still drive and go for short walks with the dog (on the days his knee and hip cooperate).
Does not like card games, board games, puzzles etc.

I feel like the cruise director, but I’m not very good at it. Following for ideas.