לא תעשון אתי אלהי כסף ואלהי זהב, Commandment 39 forbids us to construct a silver or golden deity as a partner of G–d. 
The Zohar on Parshas Yisro, explains this mitzva this way.
לא תַעֲשׂוּן אִתִּי, אִתִּי: כְּלוֹמַר אוֹתִי, Don’t make Me into silver or golden deities.
This Mitzvah 39 connects me to the tefillah of Dovid Hamelech we say in Hallel, Tehillim (115)
עֲצַבֵּיהֶם כֶּסֶף וְזָהָב מַעֲשֵׂה יְדֵי אָדָם, Their idols are silver and gold, the work of men’s hands.
If one trusts in anything to save them besides for Hashem it will lead to depression as there is no salvation from any other than Hashem.
I imagine that if one approaches Hashem as a limited being; as a being made up by human hands it is a component of making Me [Hashem] into a gold and silver idol. In other words it is if we make the mistake of thinking of Hashem in human terms. Doing so leads to great disappointment, even depression as I understand based on the Radak’s explanation.
However, Hashem gave us a map in this mitzvah of what is truly possible in a relationship with Him and how not to fall into the trap of limitations.
We are able to relate to Our Creator and access infinite possibilities. I hear it as : Don’t limit Me; don’t limit you!
How do I approach Hashem when I daven?
Am I davening with the understanding that He speaks to me? Am I understanding that His Mouth is not a human mouth, but is constantly speaking to me? Am I treating His Words of Emes, of Love with proper awe?
Am I davening with the recognition that Hashem Listens to Me without delay? Or, knowing that my tefillos, my every word is being heard by My Creator? What would I tell and daven for to The One Power Who listens to me and has all the Power to respond?
Am I understanding truly, that every sound, every step, every touch, every sight is only because Hashem empowers us and is from Him?