End of a Chain

Enjoy life. Why? To understand the complexity of life, one must understand the beginning. In this beginning, should it actually exist, we are the end in a chain of a very long list of events. How many planets have tried to develop and never were able to support the right mix of hydrogen and nitrogen and oxygen in the atmosphere to support life? How many ancestral species have predated the current human? If we think of life as a constantly-changing and fluid evolution, how amazing is it that we should exist at this point and time in the evolutionary chain?