So the Egyptian army is chasing the Israelites and they are all panicking. As you do, when the most powerful army in the world is after you, and the chances of you defending yourself on your own are worse than your chances of winning the record-setting jackpot in the lottery. So Moses says, "Hey, Lord? Kinda need your help, here." And the Lord answers, "Why are you crying out to me? Tell the Israelites to move on."
I can only suppose that Moses already had these orders, since God asks him what he thinks he's doing, instead of assuring him that everything was under control. So they move on, and you know the rest of the story.
Now I'm not one to violently drag modern-day application out of a story that happened long before I arrived in the world. But when I heard this, I really started thinking about all the times in my life when I just sit around and wait for divine inspiration to strike (as it were) instead of just doing the things I already know to do. That's a bit like watching my neighbour's house burn down while I stand in my yard, hose in hand, thinking, "I wonder if I should use this?" I want to be someone who acts, not someone who spends my time wringing my hands and asking, "Where are you, God? What should I do?"