How to do all things:

At any given moment in time, we are what we are; and we have to accept the consequences of being ourselves. Only through this acceptance can we begin to evolve further.
[...]
In general, mankind almost always acts with attachment; that is to say, with fear and desire. Desire for a certain result and fear that the result will not be obtained. Attached action binds us to the world of appearances; to the continual doing of more action. But there is another way of performing action, and that is without fear and without desire.
[...]
People often confuse non-attachment with fatalism, when in fact, they are opposites. The fatalist simply does not care. He will get what is coming to him. Why make the effort? But the doer of non-attached action is the most conscientious of men. Freed from fear and desire, he offers everything he does as a sacrament of devotion to his duty. All work because equally and vitally important. It is only to the results of work - success or failure - that he remains indifferent. When action is done in this spirit, Krishna teaches, it will lead us to the knowledge of what is behind all action, behind all life: the ultimate Reality. And, with the growth of this knowledge, the need for further action will gradually fall away from us. We shall realize our true nature, which is God.

Appendix II, The Gita and War
Bhagavad-Gita: The Song of God
translated and appendix presumably written by: Swami Prabhavananda and Christopher Isherwood

.........

"My God, give me the grace to perform this action with You, and through love for You. In advance I offer to you all the good that I may do, and accept all the difficulty I may meet therein."

The Direction of Intention
St. Franis DeSales

Going to Salesianum (House of DeSales) High School, I had to say this at the start of every day and every class. Simple and profound, and highly compatible with the above sentiments.