On the surface, gratitude appears to arise from a sense that you're indebted to another person for taking care of you in some way. But looking deeper, you'll see that the feeling is actually a heightened awareness of your connection to everything else. Gratitude flows when you break out of the small, self-centered point of view and appreciate that through the labors and intentions and even the simple existence of an inconceivably large number of people, weather patterns, chemical reactions, and the like, you have been given the miracle of your life, with all the goodness in it.
The truth is, you are supported in countless ways through each moment of your life. You awaken on schedule when your alarm clock beeps—thanks to the engineers, designers, assembly workers, salespeople, and others who brought you the clock. Your morning yoga practice is the gift of generations of yogis who observed the truth and shared what they knew; of your body (for which you could thank your parents, the food that helps you maintain your good health, doctors, healers, and the "you" who cares for that body every day)—the list goes on.
If you're like most people, you notice what goes wrong more often than what goes right. Human beings seem hardwired to notice how reality fails to meet some idea of how they think things should be. How many times a day do you sink into disappointment, frustration, or sadness because others haven't met your expectations? If you limit your attention to how life lets you down, you blind yourself to the myriad gifts you receive all the time.