Apparently "UK girls becoming more unhappy."  So an article on the BBC news site says this morning 

The piece cites a study on behalf of The Children's Society that has found that 14% of 10-15 year old girls are unhappy with their lives and 34% are unhappy with their appearance. If you read on you'll find quote after quote which state the cause of their unhappiness as being how they feel about the way they look. Especially when they compare themselves to their friends and celebrities. Many of them know in their hearts that the selfie's are faked and the shots of the stars are photoshopped, but they still can't stop themselves feeling down, because they are not as thin or brown or possessors of such perfect eyebrows.

When we look for happiness in our self-image we will always be losers. Even if we can maintain a brief level of contentment with appearance, the Bible says our bodies are in bondage to decay, so sooner or later everything starts to go a bit wrinkly or saggy. And no amount of surgery can hold back the tide of ageing (though it can make your skin look strangely tight- like someone has cling filmed it onto your face!).

Happiness in the Bible is found not in our opinion of ourselves, but in God's opinion of us.

The Bible levels the plain of our beauty by telling us that we are all ugly! Our lives are marred and scarred by our sin; our selfishness and self rule expressed in thousands of little (and large) unkind actions. We have all sinned and fallen short of the beauty that we were created to express; the Glory of God (Romans 3:23). 

And yet we are still loved. Deeply loved. Sacrificially loved. Faithfully loved. Passionately loved. Loved by a Father who sent his own Son to die for us. Loved by a Son who willingly bore the ugliness of our lives in his body at the cross, so that we could be given the beauty of His life. The status of child of God.

Jesus wants us to know His happiness. So he tells his disciples in John 15:9-11 As the Father has loved me, so have I love you. Now remain in my love. If you keep my commands, you will remain in my love, just as I have kept my Father's commands and remain in his love. I have told you this so that my joy may be in you and that your joy may be complete. My command is this: love each other as I have loved you.

Happiness (Joy) is found by experiencing the love of God in Jesus and then loving others with a sacrificial love. Not in trying to love yourself as you look in the mirror.