Your legs will notice it quickly: today is easy going. There’s a bit of climbing, but the route mostly wants to head downhill. Descending more than 570 metres is harder on your knees than on your lungs, so walk by feel rather than by pace.
With a little over five hours of walking, there’s no need to rush anywhere. You can stop more often, to drink or simply to take in the view. That way you’ll arrive in Boissezon with energy to spare, which makes a nice change. The afternoon is then yours: washing, stretching, a nap.
Take it easy and enjoy a day that asks nothing of you.