We all remember some high school coach, be they real or a Hollywood incarnation, pumping up the team with a rousing speech ending with "Failure is not an option." Well I'm here to tell you that failure is indeed an option. In fact, it's the only mindset that will allow you to truly achieve something great.
Removing failure as a possible outcome puts you on the defensive.
If the option of failing is taken away from you, you are naturally put on the defensive. You behave in a much more conservative fashion. Your forward progress is held back by the fact that your guiding principle is, "This simply cannot fail." You won't allow it. Perhaps your reputation or public image is hinged on it, or even your income. So you don't take nearly as many chances, meaning you can't achieve the lofty rewards that come with lofty risk. Progress happens in smaller, more tentative movements.
Giving yourself permission to fail frees you.
By including failure as a possible outcome (and believe me, it often is) you free yourself to take more chances, with greater risk. This is not to say you have any less to lose than someone who feels failure is not an option - you are simply giving yourself permission to include failure as a possible outcome of your endeavour. Including failure as an option takes courage. It's difficult. But if you allow it, risks can be taken that put you on a much more aggressive path. Progress can happen in faster, more dynamic movements, and this is the only way to achieve those truly lofty rewards.
Think about the underdog team in the big game. They're down by a huge amount, but they come back to win it all in the end. Why? Because failure had become a truly real option for them. They had nothing to lose because all signs already pointed to loss. Conversely, the leading team became too accustomed to the idea of winning, and failure was removed as an option. They became too possessive over something they didn't actually possess. They started playing defensively while the underdogs went on the aggressive. Momentum swings, the good guys come back, and someone wins an Oscar. You know the drill.
Fail often. Fail fast.
The idea for including failure as an option is that if your endeavour is going to fail, it should fail quickly. The slow death of a mediocre undertaking can be truly depressing. Get into the game knowing that not only is failure a possible option, it may in fact be likely. This mindset will allow you to get in and move quickly so that if it really will fail, it will fail fast. This frees you up to win big or to move on and seek out the next opportunity.