I'll start off with this question and ask follow-up questions as the thread develops.*
What is the purpose of prayer, if at the end of the day it all boils down to the acceptance of God's will being done, whatever it may be?
*(I'd like responses in the form of individuals' beliefs, not groupthink "we" type answers. What do you personally believe? Thanks.)
The main purpose of prayer is not "getting what you want from God".
Prayer is communication with God. It opens our hearts to Him, and can allow us to experience Him. If we are able to eventually learn to be continually in remembrance of God, and experience Him as a continual Presence, we will have accomplished the apostolic admonition to "pray without ceasing".
Prayer changes us.
And with maturity, we come to realize that "what we want" might not be what is best for us. We learn that God always has the best good in mind, and that He alone is wise enough to know the future, the inside of men's hearts and minds, and know what that best good is, and how to accomplish it. He alone has the power to bring it to pass. Our place, when we are able to grow into it, is to trust Him in this.
Remember Christ's own prayer in the Garden of Gethsemane - "if possible, let this cup pass from me" (that He could avoid the events of the crucifixion that were about to come to pass) AND YET He also prayed "not My will [His human desire] but Thy will [the Divine purpose/will] be done." In the end, for all, this was best, and according to God's plan. That is the ultimate example of this concept.
Even if what happens here is difficult for us as humans, if we consider the truth that in the light of eternity, this present life will seem like a puff of smoke, we can appreciate God's desire for our being united with Him in eternity, rather than turning from Him in our torment.
Reading some of the formal prayers of the Church might help illustrate these points. If you search for "Morning Prayers", "Prayer of the Hours", or "Evening Prayers" online, that should turn up sources.
Seeing how prayer may be done helps to make some of this clear. There is nothing wrong with extemporaneous prayers (and we should all pray "our own" prayers) but seeing how the Church has traditionally taught prayer can really illustrate some of the answers to your questions.