It's happened to you or someone you know: You think your car is in Park and begin to exit your vehicle, and then it starts to roll. Now, most drivers catch themselves that moment, step on the brakes, throw the gearshift into Park and wait for their heart rate to come back down. This was not one of those times.
There are some steps you can skip, and others you can't. Forgot to wash that apple before you took a bite? Not quite sanitary, but it'll still be edible. But if you forgot to, say, untie your boat before you set sail, you're not going to get very far.