I grew up overseas in Indonesia where having hired servants in the home was the norm. It wasn’t because we were wealthy, it was just the culture to hire a couple of locals to help with the menial duties of the household. Looking back I learned a lot about how to serve at the altar not necessarily from watching priests but from observing these servants. When you called them, they came; when you sent them on an errand, they would do just that—without hesitation. The more seasoned servants would anticipate what you needed and would do it out of a better sense of duty.
The difference between a servant and his master and between a server and a priest is that a servant performs their duty out of obligation—they have a contract to fulfill and a paycheck to earn. On the other hand, an altar server “works” for zero pay and does his duties out of love for God (through the priest) and for the Eucharist.
Much of what we do at the altar—bringing the sacred vessels to the priest at the altar, holding the Missal, etc—all these things can be done by any one of any age. How we do it will reflect our love for Jesus. Prayer is very much the same—how we say our prayers reflects our relationship with God. At the altar, how we serve is our prayer and how we serve is important. When training servers I always tell them to pray as they suit up: “Lord let me serve You in the Mass like it is my first Mass, but also let me serve You like it is my last.”