I wish I could read a document while using a step climber. I find that I get focused on the reading, and stop moving. Then I focus on moving for a bit, and lose comprehension. Then I have to read that section over, and stop moving. Rinse and repeat.
I usually have to stop while I write comments and occasionally if I start thinking about something a lot I'll stop. But overall in 20-30 minutes I still get 10-15 minutes of climbing. I don't have that many meetings so this usually only happens 2-3 times a week for me.