In the words of Aristotle, "it is necessary to stop." You start with empathy and common sense, and remain open to new information, but realize at some point you gotta sign off and just make whatever you consider the most ethical choice; this includes balancing how much you feel it worthwhile to worry about an essentially "negative" decision vs. other positive possibilities.

With respect to environmental harm, these are usually accidents of bad practices more than necessities of, say, eating tofu.

Thus far, killing animals has been pretty closely tied to eating their flesh.

Separating those two is also exciting to me.