Came across this little video where McGilchrist gives a very brief description of a meditative exercise he uses to balance attention of the two hemispheres: keeping your attention both focused and broad.
Gurdjieff's body sensing exercises, and meditative relaxation exercises in general, will seem to accomplish this. For example, Gurdjieff would get you to focus on one body part (maybe "filling it" with "sensation"), then another, then both, eventually until one was sensing one's full body. The limits are endless, e.g., you can incorporate all kinds of sensations: pressure, temperature, sound, vision (if eyes are open). One of the goals of the self-remembering exercise was to learn to enter into this state of maximal attention, and then recall it at will. I think some of his other exercises (e.g. imagining one's body as hot or cold) were perhaps designed to facilitate this calling up known "states" at will. But regardless, focusing and broadening attention seems a good way to balance hemispheres!
Gurdjieff's body sensing exercises, and meditative relaxation exercises in general, will seem to accomplish this. For example, Gurdjieff would get you to focus on one body part (maybe "filling it" with "sensation"), then another, then both, eventually until one was sensing one's full body. The limits are endless, e.g., you can incorporate all kinds of sensations: pressure, temperature, sound, vision (if eyes are open). One of the goals of the self-remembering exercise was to learn to enter into this state of maximal attention, and then recall it at will. I think some of his other exercises (e.g. imagining one's body as hot or cold) were perhaps designed to facilitate this calling up known "states" at will. But regardless, focusing and broadening attention seems a good way to balance hemispheres!