What was their problem?
A barren womb.
In Abram and Sarai's day, this wasn't just a desire to have children. Not having an heir meant the future of their line was in jeopardy. To some it meant that they weren't seen favorably by God. It meant that Sarai's worth was in question. Let's read:
"Now Sarai, Abram's wife had borne him no children, and she had an Egyptian maid whose name was Hagar. So Sarai said to Abram, 'Now behold, the LORD has prevented me from bearing children. Please go in to my maid; perhaps I shall obtain children through her.' And Abram listened to the voice of Sarai." Genesis 16:1-2
If you know the story then you know what happened next. Hagar got pregnant and then lorded it over Sarai. Sarai was hurt by this and blamed Abram for Hagar's attitude toward her. Abram told Sarai to do whatever she wanted to do so then Sarai treated Hagar harshly. Hagar ran away. God confronted her. Told her to go back to Sarai, let go of the nasty attitude, and gave her a promise of a strong future for the son she was carrying. She was carrying Ishmael who is the father of the arabs, of the middle-eastern people who are not Israelis.
It's easy to blame Sarai here, but she was doing exactly what we often do. We turn to the world for solutions to our problems rather than wait for God. God had promised Abram a son. If they had waited the Middle East wouldn't be what it is today. If they had waited they would have saved themselves a whole lot of heartache; would have saved 1000s of people a whole lot of pain and suffering. But they didn't wait. They thought and worried and finally convinced themselves that God wanted them to do it the world's way.
Think about problems from your past. Think about those times you didn't wait for God, when you took the easy way out and "fixed" the problem yourself. Are you still paying for those fixes? I know I still have consequences to deal with from times I went ahead of God; times my faith faltered; times I let stress or panic lead me rather than God.
We can tell ourselves the choices we make day-to-day don't matter, that no one sees them anyway, that they aren't about important things. But every choice we make matters. Every choice speaks faith or fear into the world. When we wait on God, when we do it His way, the world gains more light -- a light that will shine through time and get bigger as it goes.
You matter. God is using you even if no one else sees what you do. Don't fall under the spell of the world that says you need a bunch of "likes" on social media or that you need people to see what you do for it to be important. That isn't how God works. He sees you. Those are the eyes that matter. He's chosen you. Choose Him and His ways. You'll never regret that choice.
"Yet those who wait for the LORD, will gain new strength; They will mount up with wings like eagles, They will run and not get tired, They will walk and not become weary." Isaiah 40:31