Paul is writing to the church in Philippi and he opens with some questions. His questions are asking them to think about how they feel about their church. Are they being encouraged? Are they feeling united with one another? Paul has probably heard some complaints from those at the church about their feeling of belonging and Paul wants to address the issue.
Paul's message isn't one telling the church to be more hospitable but to those who don't feel they belong. He tells them to think outwards rather than inwards. Think about those in the church and how they can serve them more than how they can be served by the church. Through their service they would have a sense of belonging, not by being served. God wants to partner not just serve.
Paul then point's to Christ saying that they need the attitude of Christ. Christ was God but he didn't claim that God status. Instead of being served and worshipped on earth as God should be he humbled himself to be a servant to mankind, all the way to dying for them. Because of his humbleness on earth he was elevated to sit at the right hand of the Father, a place of highest glory. Humility brought glory, serving brings belonging.
Philippi needed an attitude check. Don't complain about the duties and tasks. Don't complain about the people whom you are with and the people you are called to serve. In comparison with Christ you have nothing to complain about for his suffering is more than we can ever experience. Even if you feel like your service means nothing, the smallest thing God uses for greatness.