Interesting example, but if you don't say it's yours, someone can assume it's a gift left by someone. It doesn't require fighting, but speaking. The other who doesn't want to be moral will be the one who instigates violence in a physical manner, and that's why there is work to fight for what's ours because others don't care and just want to take even when it's not theirs.

But we do belong to ourselves. How we treat ourselves in another issue apart form self-ownership.