I settled on using a mental image due to the fact that I couldn't help controlling my breathing when I focused on it. I find that it's harder to hold your focus

I settled on using a mental image due to the fact that I couldn't help controlling my breathing when I focused on it. I find that it's harder to hold your focus on an image than an automatic bodily function, but the tradeoff is that it's easier to disassociate. After enough practice, you may even start to disassociate from your anxiety (as in be able to view it metacognitively, be aware and become friends with it rather than get rid of it).