The Covenant of Survival states:
Some must die, so that others may live!
Recognizing this pattern in the world, I began to focus on simply minimizing pain & maximizing pleasure (in my own life, as well as those with whom I come in contact)...
I am also rather fond of Callahan's Law (also known as the Law of Conservation of Pain and Joy):
"Shared pain is lessened; shared joy, increased — thus do we refute entropy."
Stated another way: "Just as there are Laws of Conservation of Matter and Energy, so there are in fact Laws of Conservation of Pain and Joy. Neither can ever be created or destroyed. But one can be converted into the other."
Many people are familiar with a related concept through the Wiccan Rede, "An it harm none, do as thou wilt." This concept has roots in everything from Hippocrates & Saint Augustine, to Rabelais & Crowley. My research concerning sources of the phrase can be found in this post: Fay çe que Voudras (Although ultimately, I'm actually rather fond of the simplicity of Saint Augustine's maxim, "Love, and do what you will!")
The Wiccan Rede does seem to work in most situations... even in BDSM, it's not okay to harm others (although through being hurt carefully, one can produce endorphins that lead to an altered state of consciousness)... but we live in a world where people fight over resources that are perceived to be limited, and there are many folks who are willing to kill you for your stuff, before you get any similar ideas (even if it's just a distribution problem, the Malthusian conspiracy of scarcity hasn't yet been defeated by post-scarcity methods, such as pronoia, gift culture, the long tail of abundance, &/or the design science revolution).
I must say that I do enjoy the company of people who attempt to live their lives with the concept of Ahimsa (a Sanskrit term which means, "avoiding violence" ...about which, Ghandi had this to say: "In its comprehensive meaning, ahimsa or non-injury means entire abstinence from causing any pain or harm to another living being, either by thought, word, or deed."). However, I do not personally believe that it is possible to completely prevent violence from occurring in this world. One may certainly show compassion to the animal or plant that one kills, in order to survive oneself. And perhaps this kindness is really what is at the root of this concept; but how can we live in this world completely without suffering? Although, I will admit that when it comes to answering such questions, I tend to travel a moderate path, myself. I wish good fortunes to whomever thinks that it is possible to do no harm... I would just ask for you not to beat yourself up too much, if you happen to accidentally crush the insects as you attempt to sweep them out of your path ;~}
Similarly, this is the way that the pertinent section of the modern Hippocratic oath is phrased: "To practice and prescribe to the best of my ability for the good of my patients, and to try to avoid harming them."
Even if you don't believe that plants can feel pain, then I would hope that you at least still want to minimize the suffering that animals feel when they are slaughtered by the human or mechanical butcher (which definitely harms them, but they're not people, so maybe that's different?). Buying shrink-wrapped meat @ the grocer, it's so easy for people to ignore such things; but I am glad that there are people like Dr. Temple Grandin in the world, who are able to help people develop ways to show more compassion to our livestock.
I also want to encourage all of us to reduce the amount of our impact upon the world in general, in general... by minimizing our ecological footprint & maximizing our sustainability.
When I look at the deplorable state of the modern food industry through the work of Michael Pollan, I am glad to see that there is a clear answer to the 'Omnivore's Dilemma:' "Eat food. Not too much. Mostly plants."
But, just in case you thought that eating plants is a way to step outside the cycle of harming "sentient" creatures, please recognize how much of agribusiness is fueled & fertilized by petroleum... which is procured through much human bloodshed! "America's seemingly endless supply of cheap food, whether grown industrially or organically, 'is floating on a sinking sea of petroleum.'"
Although, I suppose if you're a breatharian, then you don't have to worry about eating food, right? %~&