Let each of you look not only to his own interests, but also to the interests of others. (Philippians 2:4, ESV)The word translated "interests" is not in the original text. This could be read, "...look not only to yourself, but also to others." You can see that, even as we read this in English, the word "interests" is implied, but could also be substituted with words like "needs" or "wants".
What is important, is that this verse continues the previous thought of humility. This is a practical way to think of humble living. It isn't a complete abnegation of oneself. Everyone is naturally in tune with their own interests, needs, and wants because we live within ourselves. The way to humble living is to take yourself, out of yourself, and look through others' eyes.