Can someone look into a mirror and not liking what he or she sees be capable of loving his neighbour? The greatest command is to love your neighbor as yourself... ??
In order to love God and neighbour, we must first truly love ourself. This is not an option, but rather a necessity. If one hates oneself, how can on love God who he does not see or have true charity towards another person.

We can still love ourselves, while momentarily disliking ourselves due to our personal shortcomings or sins.


  “Teacher, which is the great commandment in the law?” Jesus replies: “You shall love the Lord your God with all your heart, and with all your soul, and with all your mind. This is the great and first commandment. And a second is like it, You shall love your neighbor as yourself. On these two commandments depend all the law and the prophets” (Matt 22:35-40).


St. Thomas Aquinas affirms that in order to love God we must first love ourselves.


  That the love of God and love of neighbor are profoundly connected is widely acknowledged and often preached. After all, did not the Apostle John declare that anyone who says that he loves God but hates his brother is a liar (1 John 4:20)? But where does the love of self come into this? Save for the word of Jesus, we might be tempted to leave it out altogether. We hardly need to be encouraged to greater personal aggrandizement. Yet here is our Lord exhorting us to love others in the same way that we love ourselves. That would seem to imply that the former rests upon the latter. Can that be right? Fr Herbert McCabe thinks that it is, and he appeals to no less an authority than St. Thomas Aquinas.
  
  When we examine Jesus’ words closely, we find two commandments but three objects of love—God, neighbor, self. It is the third, McCabe claims, that is the key to the others. Self is where we start from:
  
  
    I don’t mean that it is more important to love ourselves than to love God. I just mean that loving yourself is the way you love God. I mean that loving yourself is, in a way, more important than loving your neighbour because, without loving yourself, it is quite impossible to love your neighbour. Aquinas says, we should first love God, then ourselves, then our neighbour, then our bodily life (Summa Theologiae 2a2ae, 25, 12). (“Self-Love,” God, Christ and Us , p. 69)
  
  
  McCabe suggests that to understand what it means to love God we should reflect on what it means to love ourselves—and to not love ourselves. We fail to love ourselves, asserts the Dominican theologian, when we base our lives on the false belief that we lack intrinsic dignity and worth:
  
  
    The root of all sin is fear, a fear which is a disbelief in oneself, the fear that really, in oneself, one does not matter, does not really exist—the fear that if one really looked into the centre of oneself, there would be nothing there: the fear not just that one is playing a false part, wearing a disguise, but that one is nothing but the disguise. It is this fear that gives rise to the desperate attempt to put something there, to make something of ourselves, or the desperate fight to prevent others making nothing of us by taking away the masks. And so we make ourselves somebody through power over others and through possessions, which are a sort of power. Or we sink into some distracting pleasure so that we can forget the emptiness. And, of course, we hate those who threaten our self-flattering images. And all this is rooted in fear, because we cannot believe in ourselves, because we cannot believe that we matter just because we are ourselves. It is rooted in the fact that we cannot love ourselves. (p. 70) - To Love God We Must First Love Ourselves