From the YouCat (Youth Catechism):
Why did God give us “passions” or emotions?
We have passions so that through strong emotions and distinct feelings we might be attracted to what is right and good and repelled from what is evil and bad.
God made man in such a way that he can love and hate, desire or despise something, be attracted by some things and afraid of others, be full of joy, sorrow, or anger. In the depths of his heart man always loves good and hates evil—or what he considers to be such.
Is someone a sinner if he experiences strong passions within himself?
No, passions can be very valuable. They are designed to lead to and reinforce good actions; only when they are disordered do the passions contribute to evil.
Passions that are ordered to the good become virtues. They then become the motive force of a life of fighting for love and justice. Passions that overpower a person, rob him of his freedom and entice him to evil, we call vice. (YOUCAT questions 293-294)