If you live near water, kayaking can be an incredibly immersive pursuit in nature that doesn’t really tax the body (unless you want it to)
Trail running is another one of my favourite things to do, but while much safer than MTB still can have some risks… minimal though, comparatively speaking
My go-to is to ask what they like to do in their spare time.
A lot of the time you’ll get answers about how they have none or how it’s filled with chores, but you can always redirect and say, if you suddenly had a bunch of free time just for yourself, and you couldn’t use it to work, what would you fill it with?
In my mind the latter gets you down to what brings them joy, and in some cases how they want to see themselves, which can tell you a lot about a person.