When I was in the Reserves, this used to be a real problem for me. I had a hard time standing in formation for long periods. My back hurt so bad, because I have a swayback and some neck problems.
Now I periodically spend all day on my feet manning tables at conventions. 9am to 5pm, two to four days in a row. And my back doesn't hurt at all, even though I still have the same physical issues (and I'm not in anywhere near as good shape).
Here's what I've learned...
If you don't have to stand still, don't.
It doesn't matter if you're confined to a small area, such as a line, you can still move. Bounce from foot to foot. Shift your weight. Tap your toes. Move your arms and hands when you talk. Look around. If there's a railing, don't just lean on it, bounce on it - push yourself away and let yourself fall back against it. Rock back and forth heel to toe. Jump a few times on the balls of your feet.
Basically, act like you're hyperactive. After a bit, it becomes habit.
And it's not as exhausting as it sounds. After a long day on your feet, you'll feel WAY more energized if you've been moving than if you've tried to stand still all day.
Oh, and if for some reason you do get stuck having to stand perfectly still (highly unlikely in a place like Disney) then focus on tightening and relaxing your calf muscles, and shifting your weight from foot to foot.
Good luck!
