She gives several examples of actions that can seem futile -- building something that a single storm can blow away, or praying when your prayers seem not to be answered, or loving someone who can so easily discard you. Each time the stanza ends with "do it anyway."
It's a message of hope and determination. We mortals can't know the end from the beginning, so what matters is that we keep setting our feet on good paths and staying with them.
I was talking on the phone the other day with a good friend who has wrestled with crippling depression for many years. He described a feeling of such despair that it hurt me just to hear about it. He had a friend who had expressed an interest in the gospel, but, he said, "I felt so overwhelmed by my lack of understanding, my own weakness, that I felt like I had nothing to offer him."