/u/Iphikrates has previously answered:

• I'm a farmer in 500 BC in a typical Greek city-state. How often will I get called to mobilize for a battle?
• Modern armies generally cut off recruitment in the 30s or 40s, but in ancient or medieval armies, we see men taking the field well into their 40s or 50s or even older. Were older men more physically fit at the time?
• Why were hoplites so common in the ancient world?

Sorry for my English, not a native speaker.