In the book of Genesis 17, Abram is now ninety nine years old. He had left his home in Ur when he was in his seventies. During that time God had given him some amazing promises that still had not been fulfilled. Now at ninety nine the Lord speaks to Abram again. This time the Lord tells Abram to change his name to Abraham. The Lord also confirmed His earlier promise that Abraham's wife Sarah, would have a son in her nineties. However at this point in his life Abraham in essence says to the Lord, " you don't have to do this. I'm old, were fine, we have another son named Ishmael. Can he be the son of promise instead?" The Lord refuses to accept Abraham's alternative. No, the Lord had made a promise and He was going to fulfill it. Abram was now to Abraham, Sarai was now to be called Sarah, and Isaac was going to be born within the year.
It is difficult to wait on the Lord for His promises to be fulfilled. Patience doesn't come natural, nor is it hereditary. Sometimes we get to the point where we want to offer an alternative, or an easier route, or tell the Lord to forget it all together. If the Lord is gonna "change your name" so to speak, or bring "the promise" to pass, let Him. The change may come unexpectedly, but it will be a blessing in the end.