I cannot imagine myself as a helium balloon. I can imagine a helium balloon and attach the label "me" to it, but this does absolutely nothing for me in terms of self-image or emotion.
Attaching the label "me" to the image I see in the mirror is essentially all I do when thinking of myself as my body. What are you doing apart from that?
I don't understand how feeling like you're in the wrong body manifests as suffering.
Me either really. It just hurts when I notice it. You may as well ask how feeling a wound on your flesh manifests as suffering.
I assume you meant the wound thing as an example of irreducibly simple suffering, but actually I've spent quite some time investigating things of this kind through meditation, and they do break down further, in ways that make them much easier to deal with. In fact, physical pain is one of the forms of suffering most amenable to this.
What I was trying to get at with the balloon question is are you troubled by your body being gender A, or by it not being gender B? Is it an aversion, or a desire, or a restlessness, or what?
Attaching the label "me" to the image I see in the mirror is essentially all I do when thinking of myself as my body. What are you doing apart from that?
I can't speak for Liza, but what I mean when I talk about thinking of myself as my body (though I'm more likely to use the language "identifying with my body") is something like attending to the experiences that come from that body.
The extent to which I do this varies greatly; in particular, in certain forms of meditation I attend to those experiences to the exclusion of almost ever...
If it's worth saying, but not worth its own post, even in Discussion, it goes here.