As part of the qualifications to serve as a juror, you need to be a United States citizen and be at least 18 years of age. You should never have been convicted of a felony. One of the groups that are exempt from federal jury service are members of the armed forces who are still on active duty.
You must live in the city or county the case is in. Other than that...any citizen can be called to jury duty. Then lawyers fight over which ones they want on their cases. It is supposed to be a jury of our peers.