Isaac pleaded for his wife (Gen 25:21)

Now Isaac pleaded with the LORD for his wife, because she was barren; and the LORD granted his plea, and Rebekah his wife conceived. (Gen 25:21)
~Isaac was 40 when he got married, but God blessed him with children only after 20 years, after he had prayed for Rebekah. How could it be that Isaac was the promised son, his wedding was divinely arranged, and yet God didn't bless him with children till he had wrestled in prayer with God? And, it took 20 years for this breakthrough. We must understand that in God's kingdom things don't automatically happen. It is only those who take the risk to sow the seed on the ground who can trust God in hope to see a mighty harvest. God has put man on earth to work. He can only eat the fruit of what he sows. And, asking, seeking, knocking by faith in prayer have great results. But, how many of us take prayer seriously? Do we just sit and wait for things to happen automatically? Hebrews 11 teaches us that people did things and obtained things by faith. Faith is action. And, many times it requires untiring persistence and perseverance.