What ever you like to do!
My BFF and I are in our 50s. Sometimes we're semi-commando, but most of the time we're pretty laid-back at WDW! We're on vacation and tired of rushing around all of the time! *LOL*
There is a lot to gawk at while walking (my usual term is "walk & gawk") around WDW. Main Street in MK, in particular. Look at the windows above the shops, stop and listen to the sounds. Other have mentioned the scents, but my sense of smell ranges from non-existent to poor, so that doesn't work for me!
AK is similar, in terms of detail. I love to look at the various textures and colours!
If you haven't done it before and have time during your trip, visit the deluxe resorts on the monorail loop and/or the EPCOT area resorts, which can be accessed via the Friendship boats or walking. Mode of transportation depends on the condition of one's feet at a given time! *LOL*
There are a number of attractions at WDW that aren't thrill rides, but are very interesting, as well as live and 3-D or audioanimatronic shows. In fact, there are fewer thrill rides (Yay!) than most amusement or theme parks, considering the size of WDW!
If either of you has physical limitations or needs to exercise a bit of care (back, neck, etc.), it can be a good idea to do a bit of research. My BFF and I decided to try all of the rides (I haven't managed EE yet, but hope to my next trip), then just not return to any we disliked. I KNEW ToT would be on my list! I do not like being dropped--or the sensation of falling!

But I rode it once, just to be sure! What can I say? Stubborn is one of my middle names!

We found some rides jarred us a bit too much (Test Track and AK Safari). BTMRR also, but we're accustomed to that from
Disneyland.
The disABILITIES board is a great reference for any special needs. The moderators and most of the members are accustomed to dealing with all kinds of needs, whether it's special diet, a temporary injury or long-term limitations. They usually know the answer--or where to find it!
You can have a wonderful visit at WDW how ever you choose to do it. Strolling is just one possibility!
