1 Nephi 12 (Temptations)

In this short chapter temptation is described as something that blindeth the eyes, hardeneth the hearts, and lead toward broad paths.

I think that as we are tempted and as we sin we will blindeth our eyes. Things that we know are bad somehow become not so bad. We also tend to become very defensive about others who may try to help us (harden our hearts). We also loose our way sometimes when we sin. Our focus is changed and we become less motivated in reaching our celestial goals.

Conversely, when we keep the commandments we are more sensitive to the spirit which helps us to see upcoming troubles and temptations. When we are living the right way we also have more compassion toward others. When we keep the commandments it is easier to resist temptation and stay on the straight and narrow path.