Don't worry about anything, but in everything, through prayer and petition with thanksgiving, let your requests be made known to God. And the peace of God, which surpasses every thought, will guard your hearts and your minds in Christ Jesus.
(Holman Standard)

1. God does not say He will grant your requests.
2. God does not explain how this 'works'. Similar to God's speech to Job, where He did not explain to Job why all the evil befell Job. God simply pointed out that He is sovereign.