Rebbe Nachman teaches:
A person should recite T’hillim, the Psalms, as though they are speaking about oneself. A person should see the words in each and every psalm as applying specifically to oneself.
In connection with this, someone once asked the Rebbe how it was possible to apply all the verses. “What about where King David praises himself, as when he said, ‘[G-d,] guard my soul for I am a chassid (pious)’?” (T’hillim 86:2). The Rebbe answered, “A person must judge himself favorably, at all times. Doing this allows the person to be a chassid in at least that one good point.
We see this in our daily liturgy. At first we say, ‘Who are we? What is our life? What is our righteousness?’ Then we say, ‘But we are Your People, the children of Your Covenant…, ‘ uplifting and encouraging ourselves, declaring ‘But we are the children of Avraham, Yitzchak and Yaakov…’ This is how one should conduct oneself in avodat (the service of) Hashem!” (Likutei Moharan II: 125)