Php 2:5 Let this mind be in you, which was also in Christ Jesus:
Php 2:6 Who, being in the form of God, thought it not robbery to be equal with God:
Php 2:7 But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men:
Php 2:8 And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross.
Let this mind be in us... What mind is that? Well it is the mind that was in Jesus, so it must be a very good mind. In the context of what was before and after this mind is a mind of humility. I find humility to be uncomfortable, as I think pride is one of my most prized and practiced sins.
Humility is not a lack of self confidence. It does not mean we think we're worthless and have no particular use to anyone else, ourselves, or society. We can be aware of the gifts we have, either through birth or development and training, because how else would we put them to good use? Jesus had humility, and He probably did not think Himself useless to society. It does mean that we are not prideful, and understand all good things like our good talents come from God and not from within ourselves.
Of course, all of that is easier said than done. There are plenty of people with no self confidence, and there are plenty of people with way too much pride. That's why Jesus is our example and not the person we see in the mirror. Jesus could have easily (and rightfully) deemed Himself way too worthy to be killed on a cross, and yet He did it for our salvation. Paul is asking in the letter for his readers to try and do the same, to be of that same humble mind and do the things asked of us, which include esteeming others as better than ourselves. Seems a lot easier than a brutal death on a cross...