God is love (1 John 4:8,16). So anything that is of God is lovely. And all things lovely are of God. This includes, but is not limited to, the love we share between one another in various relationships such as friends and family. In fact, all people are God’s creation and we are called to love them. So other people are lovely. And we should think about other people – how they are all beautifully made in God’s image. We should think about them before ourselves (Phil 2:3-4).
What else is lovely? God’s creation. The nature around us. Anything that reflects the image and glory of God. For example, it is a lovely thing to attend a wedding and celebrate the coming together of a husband and wife. On the other hand, it is not lovely to watch a husband and wife hurling insults and hurtful things towards one another. When we think about the wedding and ponder what is going on, our minds and hearts are pointed towards God and His glory. When we ponder hate and hurtfulness, our hearts and minds are pointed away from God.