(Statue of the Sacred Heart of Jesus in Alba de Tormes, beside the tomb of St. Teresa of Avila)
St. John of the Cross talks in his "Ascent to Mount Carmel" about how we are tormented by our self-will, often we are angry and frustrated (or stressed) because things don't go the way we had planned.
On the other hand, Our Lord told St. Catherine of Siena of the benefits of abandoning our self-will and uniting ourselves to the Divine Will:
"I desire thee to know that all pains which afflict men in this world depend on their wills; for if the will were regulated by and conformed to My Will, the pain would in a sense disappear. And although he whose will is thus sanctified and regulated, may feel labors and sorrows; yet what he suffers cheerfully for love of Me, is borne by him almost without pain, for he endures it most willingly, considering it and knowing it to be My Will that he should suffer....Affliction or pain proceeds from the will, and entirely depends upon it, since man is afflicted by having what he wishes not to have, or not having what he wishes. Therefore, if his self-will be removed, the spirit of man is tranquil and enjoys peace."
~ from Consoling Revelations from the Writings of
SS. Gertrude, Mechtild, Bridget and Catherine of Siena
collected by The Ven. Benedictine Abbot Blosius.