Floating bones is all about the concert of tensions in our musculoskeletal system. While we can hold part of our body rigid and at tension for an hour, it is decidedly non-optimal. @Carouser points to part of the solution: holding the iPad close to your body will lower the stress on your hand, arm, shoulder, upper torso, ... actually pretty much everything! Using gravity as much as possible instead of your grip is a good idea, too. Someone mentioned using the smart cover rolled up in a triangle to hold the device -- another excellent idea.
I think some company sells some clips for the corners of the iPad with crisscross elastic bands: you just slip your hand between the back of the case and the elastic bands. All of your hand muscles can stay relaxed. Brilliant. Mindful movement is all about using the minimal amount of aggregate structural tension to stand, move, and do work.
The one most people miss: train yourself to shift off which side is holding the iPad. Every few minutes, shift the computer to your other hand. This will be incredibly difficult at first. It may takes weeks before feeling comfortable shifting and many more weeks before it becomes automatic. If you are a heavy iPad user, doing this one thing can have a huge impact on your long-term structural health.
