Answer:
Here's my thought. Since human sacrifice and obtaining candidates for human sacrifice dominated much of Aztec life, warriors and those who were sacrificed received great glory and honor for what they did. But the trade-off of this was that life could be tenuous and short. How did these conditions for life affect how the Aztecs viewed death? Many people in the past and today believe that if people have afterlives, what a person's afterlife is like is determined by how that person lived. In contrast, the Aztecs believed that how a person died determined what that person's afterlife was like.
There were different realms a person could go to in their afterlife. Warriors who died in battle or by sacrifice either went to a paradise in the east and joined the sun's rising in the morning, or joined the war god Huitzilopochtli in battle. Women who died in childbirth were considered just as courageous and honorable as warriors who died, and thusly went to a paradise in the west and joined the sun's descent in the evening. People who died from lightning, drowning, certain diseases, or particularly violent deaths went to Tlalocan, a paradise presided over by the god Tlaloc located within the Aztec's thirteen heavens.
In contrast, those who died of most illnesses, old age, or an unremarkable death went to Mictlan, the Aztec underworld. Once in Mictlan, a person had to traverse through a harsh terrain with many trials in order to descend from Mictlan's top level to its final ninth level. This grim path for those who died in more ordinary ways highlights how Aztecs perceived both life and death; in general, there was greater esteem for people who died from premature but honorable deaths than for people who avoided these endings and managed to grow into old age.