You are never going to have things go the way you want them. You have no control, this is no test, its a one shot deal. So if you think that by saying "Oh, I will get it next time" that you are buying yourself more time, you are not. You are just trying to justify your inability to try harder, your unwillingness to do your best, your pure unadulterated laziness.

You have to do your best ALL the time, because you might NOT get that next time. You need to understand that you CAN do it the first time because you are NOT alone. Once you get that in your weak mind, you wont be weak anymore. You become strengthened.