The position of warrior was an high ranking. It wouldn't be surprising to find out that your son wanted to go into the army when he grew up. As we'll see, there were also significant rewards in store for the successful soldier.
Boys in the empire would receive a good education, no matter what their prospects for a career were. Astronomy, rhetoric, poetry, history, and of course religion would all be important subjects at school. Then there would be actual training on the battlefield. A boy became a man in society at the age of 17. For a commoner wanting to go to war, this meant starting out in the lower ranks in the army. There were servants, who basically just carried weapons and supplies. Then there was the youth in training, who had not yet captured his first prisoner. That first capture was an initiation into the world of the real Aztec warrior.