The English word "content" can bring up thoughts of indifference and mild temperament. Modern usage tends to give "content" a negative connotation, as though such an attitude has little ambition or drive.
Not so of the Greek term that the Holy Spirit chose for this passage. It is composed of the pronoun for "self" and the noun for "sufficiency." Both in Scripture and in secular Greek literature, the word demands an ability to conquer whatever circumstances that may oppose one's purpose or goal and to continue through in spite of difficulties.
The context of our text is a prime example. Paul had experienced hunger and satisfaction. He knew what it meant to be obscure and to be a celebrity. There were times when he had more than enough resources to accomplish what he understood God had called him to do, and other times when resources were very scarce. In whatever state he found himself, Paul had learned to be self-sufficient.
Our problem is that we often are looking only at the physical and circumstantial issues and have not learned that our Lord Jesus provides grace that "is sufficient for thee: for |His| strength is made perfect in weakness" (2 Corinthians 12:9). The resources of the omnipotent Godhead are enough for us to "be content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee" (Hebrews 13:5).
The self-sufficiency of the twice-born rests on the eternal fact that God "worketh in you both to will and to do of his good pleasure" (Philippians 2:13). HMM III