Based on Mishnah Torah I: Book of Knowledge, the Laws of Foundations of Torah, Ch. 7
The core idea of prophecy is that it is the culmination of a relationship with God. In a relationship, you make room for the other. The center of gravity in a relationship is in between both parties — not in my needs and demands. Because of this, prophets had to get themselves in "the zone" like any person has to do when meditating. However, whether they received a prophetic "download" or what the download was about was up to what God would to reveal to them at that time, if anything at all.
The opening of the Rambam's words in this chapter:
It is [one] of the foundations of [our] faith that God conveys prophecy to man.
Prophecy is bestowed only upon a very wise sage of a strong character, who is never overcome by his natural inclinations in any regard. Instead, with his mind, he overcomes his natural inclinations at all times. He must [also] possess a very broad and accurate mental capacity.
A person who is full of all these qualities and is physically sound [is fit for prophecy]. When he enters the Pardes and is drawn into these great and sublime concepts, if he possesses an accurate mental capacity to comprehend and grasp [them], he will become holy. He will advance and separate himself from the masses who proceed in the darkness of the time. He must continue and diligently train himself not to have any thoughts whatsoever about fruitless things or the vanities and intrigues of the times.
Instead, his mind should constantly be directed upward, bound beneath [God's] throne [of Glory, striving] to comprehend the holy and pure forms and gazing at the wisdom of the Holy One, blessed be He, in its entirety, [in its manifold manifestations] from the most elevated [spiritual] form until the navel of the earth, appreciating His greatness from them. [After these preparations,] the divine spirit will immediately rest upon him.
When the spirit rests upon him, his soul becomes intermingled with the angels called ishim, and he will be transformed into a different person and will understand with a knowledge different from what it was previously. He will rise above the level of other wise men, as [the prophet, Samuel] told Saul [I Samuel 10:6]: "[The spirit of God will descend upon you] and you shall prophesy with them. And you will be transformed into a different person."