When you are involved in helping others, especially when it involves your family or community, you might feel overwhelmed with the sense of responsibility. This contributes to a lack peace of mind.
Remember the words of the Sages (Pirkei Avos 2:21): "It is not upon you to complete the work. On the other hand, you are not free to refrain from trying."
If you realize you are not responsible for what is beyond your control, you will retain your peace of mind - whatever the outcome.
Today, if a project you're working on does not produce the desired result, say to yourself, "Well, I know I tried my best. Now let's see how I can do even better the next time."
(see Rabbi Eliyahu Meir Bloch - Shiurai Daas, p.113; Gateway to Happiness, p.84)