Well, the Mendenhall Glacier is only about 13 miles from downtown
Juneau. Many who visit Jeneau choose to go on a guided walking tour of the glacier. Though, that type of tour will include some hiking along the glacier. Not sure if you'd be up to that after kayaking.
So another alternative could be a trip tour that focuses on photography. Juneau is great for wildlife viewing. You'll see animals like brown bears, whales, eagles, sea otters and the Sitka Black Tail Deer.
If you're into fishing, then there's always
fishing in Alaska as an option. In the warmer months it's popular to fish for the king salmon or the halibut.