Success rate of 0.1%? Where'd you get that statistic? But whatever the actual number, your question is an invalid one. The law of gravity works 100% of the time, except we can fly planes, right? Yes, I know that sounds silly, but it's really to show you how silly YOUR question is because "LoA" works even "negatively" (put in quotations because human perception is what labels things as positive or negative when really, the universe is 'neutral' and things don't happen as a way to punish us... that's just ridiculous, it's not personal).
You can tell if your affirmation is positive or negative by the way it makes you feel. If it makes you feel great, it is positive. If it makes you feel bad, it is negative. It's that simple. If you find yourself thinking negative thoughts, simply turn them around and start focusing on the positive. You will immediately feel better and you will be in alignment with love.
How is that one person is willing to do all that it takes to reach their goals, while another person gives in to silent resignation at the first sign of resistance? Why is one person willing to sacrifice nearly everything in order to live the life of their dreams, while others are too afraid to take the next step in fear of suffering through a catastrophic failure or embarrassment?