Some people say that you get what you want.
Others say that you get what you are.
As per this Gurbani line, both are correct since it says that what you are is what you want.
If we look at our lives, we have a million desires, many of them contradictory to each other. All of these million desires drive our thoughts, words, and actions at different points of time and with different intensities. And our character is nothing but an accumulation of all our past thoughts, words, and actions, or in other words, our desires. Thus, we are what we desire.
A true saint is the one who has just one desire in the world i.e. of the love of the lord. As Rumi, a famous Sufi saint, said:
“I once had a thousand desires. But in my one desire to know you all else melted away.”