I just get up and walk around. Go to the printer, go to the paper shredder, go to other people's offices for meetings, etc. I do that a lot; that makes me walk around the workplace a lot. I'm not much of a talker and am an introvert. But since I manage people, it's a way for me to stay in touch.
Now that said, there is an island of sorts outside of my office that my boss, another colleague and I share. And there are a couple of bar stools. I do use it often when I want to spread out some paper, and look over them standing up. I have a small meeting table in my office as well, but there's just more space to spread out at the island.