Gradius has a reputation for being pretty tough, mostly because it is. But if you do take a crack at it, you can view a secret message before you go to get your head handed to you.
First, either turn off your NES or go to any screen you want.
Then, on controller 1, hold the A + B buttons and either power on or reset your NES. Done right, you'll see this message.
And if that doesn't motivate you to do better, I'm not sure what will.