The classification of facts, the recognition of their sequence and relative significance is the function of science, and the habit of forming a judgment upon these facts unbiassed by personal feeling is characteristic of what may be termed the scientific frame of mind.
When my body gets to the point where I can no longer function or feel gratitude, then I'll leave it and become grateful again. But until then, I will appreciate what I have and not whine about what I don't have. I will feel blessed by life and the opportunity to help others see that they are blessed, too.