I think perhaps a reader phrased it best a few weeks ago:

[My husband] and I have wrestled with our “calling” to adopt years ago. We clearly felt it, and we have second guessed it almost every day since then, wondering what were we thinking? Did God really call us to this or were we just emotionally carried away, or as [this post] put it, is it an act of worship? I think in my naïveté, I assume that if I obey what I think God is clearly placing on my heart, he will “reward” me somehow with happiness and not trouble. My very wise husband points out that this is very bad theology!