"I am the Lord's servant," Mary answered. "May it be to me as you have said." Luke 2:38
Mary's response to the angel is a reminder to me that our response to God could alter our role in His plan.
I've always heard the call to action to "see what God is doing and join with Him." Meaning, God's plan and purpose will be accomplished no matter what - and whether or not I'm a part depends on my response.
We see Isaiah ready and willing when the call came asking who would go and his response was, "Here am I, send me." (Isaiah 6:8)
In Luke 2 Mary had been chosen. She was specifically picked for this mission. And yet when the angel came to her, he didn't say she was ALREADY with child - he said she WOULD BE with child. If she had responded differently than "May it be..." I suppose there would be a different story to tell. But then again, I guess her response is exactly why she was the girl for the job. She had already found favor with the Lord. And yet in that moment she could have chosen her plan over God's.
Of course, it's a reminder we're given free will. We have the "right" to choose. But when we surrender our right to ourselves, laying down the flesh and taking on the spiritual, we not only get to join in with God's purpose, we can be invited. When God comes to us with His plan, we can be ready to respond, "May it be..."