Another thing, and this is something that has made me feel grateful for my own existence, is this...
There are a lot of people out there with severe mental or physical defects, that can't enjoy their life. They may have cancer. Children may never grow past the age of 18. Parents may be grieving the loss of a child. Someone who has been to war may have post traumatic stress syndrome, or have lost limbs in war. Not to mention all the homeless and the starving people on the streets out there.
Am I going to show them how ungrateful I am, to them, for my good health, my wealth, and the fact that I have a roof over my head and food in my belly? No, my life may not be perfect, and I may be lonely a lot of the time. But everyone faces their own struggles, and to be ungrateful for what is going right in my life is to spit in the face of everyone that has so much wrong in their life. Everything could be much, much worse.