Kabbalah sur Rois 1 1:21

The second is to be careful with the Awe of God throughout the day. The pious Rabbeinu Yonah wrote, in the Letter of Teshuvah a great pillar regarding this issue in Torah, that all day long the awe of heaven should not depart from before your eyes, as it is written "Do not envy sinners in your heart, but only have awe of God all day long" (Prov. 23:17). And we need to say that the simple meaning of the verse is this, do not be jealous of sinners, rather who should you be jealous of? Of the Awe of God, in the level of Awe of God, meaning, why not be in awe of God all day long since sinners lack [the feeling of] completion as the issue of "and I and my son Shlomo will be sinners" (I Kings 1:21) - "but only have awe of God all day long" - as those who have awe of God all day long, one sees that it is needed to have awe of God all day long. And a reminder to a person who has awe is to use tefilin all day long, if possible, at least on the hours in which one deals with Torah, when they are free from worldly dealings.