How much should I urge my husband to engage in activities that stimulate his brain?

Did your husband do any of his own writing? Help other writers with editing? Would he like to do a pod cast about writing? Listen to other writers pod casts? My mom was an editor, had a wide circle of friends as writers, editors and they were constantly chatting about what they were working on. Is that an option for your husband to explore? Does he stay in touch with any former students, colleagues, or associates?
If you haven't checked, see if the basketball option has opened up, since many more people are vaccinated. If he was playing that often, perhaps there are other aspects of the game he could explore on line. Say, blogs or vlogs.

Do you think that a 77 years old man isn't an adult yet? He isn't incompetent. He has a mind of his own and he does what he likes. A former writing profesor should know what is best for him, just like you know what is good for you. What's wrong with having two different points of view?

What my sig-other and I do is watch the game shows together where we need to think what are the answers. We are both 75 and have the normal forgetfulness, especially names.

We found the game shows help us realize that we can answer some of the questions. The Game Show Network has "Common Knowledge", "The Chase", "Master Mind", where there are multiple choices in part of these games. It's a feel good feeling when you do answer a question :) Even the old game shows like "Match Game" can be fun.

Do things with him as opposed to thinking he can get motivated on his own to do more.

LUMOSITY
https://www.lumosity.com/en/

Since your husband has Alzheimer's/dementia why don't you see if you have an adult daycare center in your area that you could take him to. They serve breakfast, lunch and a snack, and offer a variety of activities to stimulate and keep folks occupied. I know that ours has been back open since April 2021, so I'm guessing most if not all adult daycares are back open again as well. They do a really great job with their clientele. Might be worth looking into.

I gave my mom a tablet years ago so she could play card and brain games on it. She's 92 now, and it's hard to know if stimulating the brain just makes the rest of us feel like we're "doing something" to stave off cognitive decline when it's not really doing anything but occupying their time. This last year my mom's cognition has made an obvious decline in spite of her reading books, using the tablet (and Lumosity app daily brain games), playing board games with me, sewing, walking her dog, talking on the phone with her grandkids, driving, being mostly independent, etc. She has an older sister who is 102.5 who retired in 1977. She reads the WSJ every day, pays her own bills and does her own taxes, and never did any of that brain stimulation stuff, never stepped foot in a gym or even owned a pair of athletic shoes, or took vitamins.

My suggestion is that if you can get your husband to adopt the use of a tablet, the games on it will keep him busy but are no guarantee to slow his cognitive decline. How would one prove it, anyway?

It may be better to have him do tasks, like sorting, pairing and attaching nuts and bolts, sorting and pairing large piles of colorful socks, building simple things from Duplos or Legos (from a plan), cutting & chopping veggies, doing housework...this will burn both mental and physical energy and gives him a sense of purpose. We do this for my 99-yr old aunt with mod/adv dementia and have her fold large piles of kitchen towels because "we need her help". We also give her colored poker chips to sort and she puts them in patterns (because she was a graphic designer by trade) and have her sort playing cards. You can find other activities for him (that don't require your participation) by searching online or just thinking about the things he did before his dementia (what did he teach?). My MIL began sitting and watching tv all day, but she was never a very engaged person to begin with. We could never get her to do much of anything after her dementia and short-term memory diagnosis. May you gain peace in your heart through this journey!

SuperiorShore, welcome!

Your profile says that your husband has dementia: was that diagnosed by a medical professional? I have found in general that along with a diagnosis, you often get recommendations for lifestyle enhancements or changes.

Perhaps a call to his doctor for clarification on how much you should nudge might help.