Why would roman citizens want to serve in augustus army

Nowhere does the Roman talent for organization show itself so clearly as in its army. The story of the Roman army is an extensive one, demonstrated in part by the scale of this chapter.
The first part of this chapter considers the history of the Roman army (concentrating on the legions), trying to explain as much background as possible. The later part of the chapter seeks to explain specific points such as various different units, the workings of the army. that's citizens want serve in Augustus army 

Idon't think any of em are right, you need to add the number of what paragraph you got your citation from