How do we know prayer with thanksgiving is effective?

Thanksgiving, when combined with prayer, is shown to produce the 'peace of God, which passeth all understanding' (Philippians 4:6-7). This indicates that when we bring our requests before God with a thankful heart, we are engaging in a faithful act that aligns our mindset with God's will. This blending encourages us to trust that our prayers will be answered and fosters a sense of peace and confidence in God's sovereignty over our lives. Additionally, the example of Jehoshaphat in 2 Chronicles 20 illustrates how praising God led to victory in battle.