I agree with the others. There is a fair bit of walking, but on most days you can take it at your own pace. The walk to the top of the buddha is the most demanding but it is entirely optional. You get to see the Buddha from the boat, so the only reason to go to the top is for the experience of standing next to the giant head and the view. There are also a number of temples, but you will see plenty others on other days. Other than that the Great Wall involves a fair bit of walking uphill.
Our group had an age range of fifties to eighties, and no one had any problems with the walking. Plenty of time to rest on the coach and in the hotel.
I put together a short video of my trip.
[video=youtube]https://youtu.be/09Rip5BvoQ4[/video]