You should keep off from Satan's enchanted ground, and not allow your minds to be swayed from allegiance to God. Through Christ you may and should be happy, and should acquire habits of self-control. Even your thoughts must be brought into subjection to the will of God, and your feelings under the control of reason and religion. Your imagination was not given you to be allowed to run riot and have its own way, without any effort at restraint or discipline.
If the thoughts are wrong, the feelings will be wrong; and the thoughts and feelings combined make up the moral character. When you decide that as Christians you are not required to restrain your thoughts and feelings, you are brought under the influence of evil angels, and invite their presence and their control. If you yield to your impressions, and allow your thoughts to run in a channel of suspicion, doubt, and repining, you will be among the most unhappy of mortals, and your lives will prove a failure.
Source: Bible Universe