I too am an omnivore, and I too recognize that my diet is problematic from some angles. I have bits of pig, chicken, cow, and fish on hand, and I look forward to eating them. I like meat. Meat has the advantage of being nutritionally dense, easy to prepare (no mixing required, just put it in the oven or in the pan) and sensorially satisfying.
It could be that the lamb, pig, chicken, cow, and maybe the cod fish too were all despondent as they contemplated their fate in the last moments of their lives. I don't approve of the way animals are raised (crowded cages, small pens, over-populated feedlots, etc.) and there is no excuse for slaughter methods that are not instant and pretty free of bungling. These methods of raising animals are not only unpleasant for the animals, but they are highly un-ecological and unsanitary.
I don't have a problem with the practice of raising animals humanely and then eating them. So, you chickens, just keep eating and clucking away. You're just about ready for a beheading. Yes, I have chopped the heads off chickens and butchered them. I've seen cows and pigs killed and butchered. It didn't dull my appetite very much.
There is a very, very large problem with raising animals for food that could be, for me, a compelling reason to switch to vegetarianism (not veganism -- the practice of people who basically hate food):
Raising animals for food is environmentally unsustainable. Never mind cattle belching up methane, which is one problem. The bigger problem now, and in the future, is producing enough food of any kind from the available arable soils. As oil becomes more expensive and more difficult to get, and as natural gas is used up for fuel and plastics, there will be much less energy available to manufacture and ship fertilizers, tillage, planting, harvesting, processing, storage and distribution.
This probably sounds far fetched to people who think oil will last forever (it won't--we've already passed peak oil), but in the future we will need to allocate a substantial part of our land to food for horses to raise vegetarian food for ourselves. Prior to the internal combustion engine, about 20% of land was needed to raise oats and hay for horses used for traction. Unlike cattle, horses can't make do on any-old fodder. They aren't cud chewers, and they have 1 stomach which doesn't ferment crude fiber the way cattle do with their 4-chambered stomach. Horses need quality hay and oats to be able to work.
Just compare a cow plop with a pile of horse shit -- there is a big difference. (YOUR TASK: find some fresh bull shit and horse shit; compare and contrast.)
If someone else who was a good cook was preparing my food, and they could do a good job making vegetable food (including milk and egg products) I'd make the switch quite willingly. I know how to make some vegetarian items, which are good, nutritious, and satisfying -- but my repertoire is limited and at this point... can't eat that many bean products.