For most of my life I have flown in economy but more recently I have started flying in CW and I even have my first F flight coming up in August. When flying in WT the cabin is big and so getting up and walking around to stretch your legs is never really an issue. I generally walk up one side and down the other using the loo on the way. However, in CW (and even more so in F), the cabin is quite small and so you wouldn't get much exercise if you just stay in the CW cabin.

Is it permitted and accepted as OK to walk into the cabin of the other (lower) classes when in flight? I have never done it because I kind of thought it wasn't allowed to walk into the higher class cabins so I guessed it wasn't allowed to walk into the lower class cabins either. Is this so? If it is permitted then I will walk the entire aircraft when I need to stretch my legs... I have a dodgy knee that benefits from a walk around every hour or two.