We’ve both adopted a vegetarian diet due to the enormously positive environmental impact incurred by doing so (it saves an immense amount of water) and it also didn’t require deviating from our principal diet of pastries, coffee, and soylent green.
We try to limit our use of disposable items (paper towels, plastic bags, etc.) and we re-use, recycle, or compost everything else as often as possible. Almost all of our travel happens via foot, bike, or public transportation. We don’t machine dry our clothes, we eat food that is locally sourced and organic as much as possible, we don’t leave the water running while we brush our teeth, and yes—if it’s yellow we let it mellow.