Sometimes our own mind is our worst enemy and needs to be cleansed by God.
At times it can be easy to avoid certain situations that could lead us to sin. All we have to do is avoid a particular place, or maybe a person who frequently leads us down the wrong path.
However, what can be more difficult to avoid is our own thoughts and imagination.
Depending on what your struggle may be, controlling your thoughts can be a difficult task to accomplish. It could be connected to pornography, or even thoughts related to gossip. Whatever it is, you will need some heavenly help.
Here is a brief prayer from the Golden Manual that can be prayed before receiving Holy Communion. It asks God to purify our mind and chase away those thoughts that assault us. With God, all things are possible and often all it takes is for us to present our need before God. If we pray with an open and contrite heart, we can be certain that he will hear our cry and help us in our need.
May this Communion deliver me from the tyranny of my bad thoughts, break off the yoke of my evil habits, and dispose me always to the practice of your holy commandments. Let nothing separate me from you, O Jesus; not the attractions of the world, nor the illusions of sense, nor the wanderings of my imagination, nor the evil passions of my heart.