When a man goes into the synagogue for prayers, he starts with reading about the sacrifices in the Holy Temple. This part of the beginning of the prayer purifies him. Then he recites from Psalms that express praises God in Malchut.
The prayers that we do while sitting have the aspect and connection to the Tefillin of the hand, Malchut. The prayers while standing is a connection to the head Tefillin, Zeir Anpin.
If the actions that define the vessel are not proper, then the prayers are flawed.
Isaiah 1:15 (please read the entire chapter)
“וּבְפָרִשְׂכֶם כַּפֵּיכֶם אַעְלִים עֵינַי מִכֶּם גַּם כִּי תַרְבּוּ תְפִלָּה אֵינֶנִּי שֹׁמֵעַ יְדֵיכֶם דָּמִים מָלֵאוּ.”
“So when you spread out your hands in prayer, I will hide My eyes from you; Yes, even though you multiply prayers, I will not listen. Your hands are covered with blood.”
This verse tells about the importance of proper preparation before we pray. We need to be clean physically and with pure heart and consciousness because our actions create and define our vessels. The words of the prayers draw the Light into the vessel, and the vessel is flawed then the Light is lost, corrupted, or taken by the negative side.
Praying is not a simple expression of words like “Please God help me and fulfill my needs….”.
The verse above reveals that God rejects our prayers when we are in the impure state. Isaiah 1:16 tells us what God expects from us. “Wash yourselves, make yourselves clean; Remove the evil of your deeds from My sight. Cease to do evil,”
We need a clean body, mind, and pure consciousness that would set our hearts properly to express our sincere and pure desires. Then we can make unification of upper and lower to establish a channel of Light that would bring us the fulfillment and support we need.