Abraham followed the faith of God. And we must follow the faith of God. The faith of God has hope when all natural hope is gone. That is the word he heard. God said he would have a son and he received God's word.
So when there was no natural evidence of he and Sarah being able to conceive a child, he had hope in God's word. Even though his body was 99 years old, he hoped in God's word. And even though his wife's body was 89 years old, he hoped in God's word.
The text says that Abraham "considered" not the circumstances. Considered means to observe fully, or to exercise the mind. He decided not to exercise his mind, and decided to believe with his heart.
Abraham believed in something that gave him supernatural hope. That kind of hope is found in God's word. For 24 years Abraham had that promise about being father of a great multitude and nothing happened. But after he started saying what God said, in less than a year he had the miracle. It didn't have to take 24 years.
It doesn't have to take 24 years for your manifestation either. If you line your words up with God's word, you'll see your manifestation a lot sooner.
There is a place for faith and patience—waiting patiently for your manifestation. But some of the long wait is not faith at work. Sometimes it's just flat unbelief, as it was with Abraham. But even though the man wavered, God didn't give up on him. He stuck with Abraham for 24 years, until he got it.
You may have an issue before you right now, and you can't see how to work it out. Don't go through this mental exercise, considering the circumstances saying, "I don't know how God is going to work this out."
God didn't say to consider the problem. He said to believe what He said. He said to repeat what He said. So decide today to drop it and believe God.
Scripture Reference: Romans 4:17-22