We begin the second chapter of Taanit with a long Mishnah describing the customs and prayers of the most intense series of public fast days. Our sages note that during the time of the Temple, the priests (Cohanim) who were on duty bringing the offerings in the Temple did not fast for the entire day. They were allowed to eat to retain their strength to do their work.
The priests would serve in shifts, with a new shift coming to the Temple each week. These shifts were further broken up into seven groups of families, each such group was responsible for one day that week. If the Temple was busy with offerings, the men of that day’s family group could call on the men of their shift to come in and assist.
The Talmud cites a related teaching that the priests who were on duty could not drink wine (or any alcohol) on the day of their service and the following night. The priests of the same shift could drink at night only, since they might be called in to help during the day. At night no new offerings were brought. Even a moderate amount of wine or alcohol was considered an impairment to the Divine service.
In Jewish wisdom, alcohol is a tool with a proper time and place. Our sages did not avoid alcohol, but used it appropriately and often in a religious context.
When you are working on an important mission or assisting someone in their critical work, that is not the time to be inebriated or distracted. Keep in mind the significance of your tasks and goals so you can keep focus. If your work is not so valuable in your eyes this is a sign that you need to reevaluate your choice of mission.
This situation also reminds us that a man should be ready to help his brothers, and not distracted by his own pleasure seeking. Sometimes a man will come to you needing urgent advice or help, and we know that men are naturally more hesitant to share their problems. If you are not 100% available, he may not open up and get the help he needs.