You remember our labor and toil, brothers and sisters; we worked night and day, so that we might not burden any of you while we proclaimed to you the gospel of God. You are witnesses, and God also, how pure, upright, and blameless our conduct was toward you believers. As you know, we dealt with each one of you like a father with his children, urging and encouraging you and pleading that you lead a life worthy of God, who calls you into his own kingdom and glory. (1 Thessalonians 2:9-12, NRSV)
For ye remember, brethren, our labour and travail: for labouring night and day, because we would not be chargeable unto any of you, we preached unto you the gospel of God. Ye are witnesses, and God also, how holily and justly and unblameably we behaved ourselves among you that believe: As ye know how we exhorted and comforted and charged every one of you, as a father doth his children, That ye would walk worthy of God, who hath called you unto his kingdom and glory. (1 Thessalonians 2:9-12, KJV)
Paul's own identity is also a big deal here. He sees himself as essentially a hard worker. He's not trying to lead anyone astray or mooch off his congregation. Not only that, but Paul treats these "kids" like he's their dad. Taking care of them, nurturing them, and making sure they don't stay out past curfew.