From Lanny Bassham (paraphrased, with my own input added): The mind can only focus on one thing at a time. In (USPSA/IPSC) shooting, it should be "shoot all A's". The rest is just to distract you from that goal. The same is true for any endeavor and life in general. Whether it be your job, career, family, relationships, etc - determine what is essential and focus on it.