"Fight only the worthy fights."
Everybody has limited time and resources, but many temptations in this world. How to achieve your goals and harness or tame your urge?
Referring back to the first commandment. It is natural that no one can fight for everything he wants. Most would prioritize and go for the biggest prize first, then the bigger, then the big, if given the same time scale.
Here is an example unique for the 21st century. We are now flooded with information from the internet and are tempted in every minute to respond to new messages from the smartphones, facebook, twitter, etc. There are two considerations. One is that the initial information is often incomplete and even wrong. What a waste if you respond with your passion and only turn out to be fooled. The other is, even if the information is correct, is it worthwhile to engage in a fight with some real or virtual person for it?
Now, how to rank the worthiness of a fight? As the first approximation, worthiness W=T*E*S/(Y*C), the higher, the more meaningful.
T is your target, a person, phenomenon, or system. We can assume the rich, famous, and powerful top the list. At a scale of 0-100, for example, a political or economic system is 100, the President of the USA is also high, while a clerk at 711 is close to 0. Essentially how much attention is or should be paid to the target per se.
E is the real or potential effects of the T's particular action, or its career or net worth or audience size, i.e., how much you expect your action, IF SUCCESSFUL, will affect T's subjects. For example, Bush's decision of Iraq War has a huge E, as it was expected to affect the life, health, wealth, properties, and other attributes of whole population of the Iraq and US (the true number might be bigger or smaller). A reporter or piece of nonsense at NYT is expected to affect many more readers than an obscure blog like this. The E of returning a T-shirt at Wal-Mart is basically what you paid for the T-shirt, not the market value of Wal-Mart.
S is your conviction, how much you are willing to sacrifice. Time, money, reputation, career, health, even life.
Y means you, with the same scale as T. Incorporating Y helps an "objective" observer to compare different Ys and Ws.
C is the cost and risk for actually challenging T, including not doing the other things you would have done with the same amount of time and energy. Similar but not identical to S.
This formula is obviously simplistic. Just point out a few issues here. First is that it does not relate to a person's official duties. A firefighter has a job of fighting fire; evasion is not an option.
Second is that the formula says nothing about how to fight (though reflected in S and C) and the legality.
Third is that T, E, and S are often not independent, so the formula sometimes overestimates the numerator. A president, not a 711 clerk, can instigate a war. Stopping a war is much harder than returning a merchandise at Amazon.com.
Fourth is that it says nothing about the prospect of succeeding. Before one does anything he typically has an idea of how much he can achieve his goal, then he will partition his time and energy for it. Hence, S and C are flexible, often interrelated, and related to one's selfishness or selflessness. Although challenging the big guys on big issues has the most significant, potential outcomes, few people do it because the chance of winning is tiny, and most automatically assign a small S and big C. Nonetheless, chance of winning could still be partially revealed by W assessing risk and reward.
A saint considers W=E on only morality not monetary values, with no regard for other factors. For a mere mortal, it seems utterly a waste arguing on any internet discussion boards or twitter.
Note: These ten commandments summarizing largely accepted principles in the modern world are simple and may have been advocated by others before in a different shape, way, or form. Just like Moses' Decalogue, which only stipulated common codes of conducts at the time, with religious messages.