It is not enough to watch our circumstances to detect the times of temptation. We must also watch our heart to know when temptation might approach us.

We need to know our own heart, our natural disposition, and the lusts, corruptions, and spiritual weaknesses that beset us. . . . David tells us he considered his ways and kept himself from the iniquity to which he was prone (Psalm 18:23).

Just as people have differing and distinctive personalities, so they are also affected by distinctive temptations. These relate to their nature, education, and other factors. Unless we are conscious of these propensities, relationships, and dynamic possibilities, temptation will constantly entangle us. This is why it is so important to know ourselves.

John Owen, Sin and Temptation