|The Circle of Life|
In the first siman of the Shulchan Aruch, the Rema writes, "I place Hashem before me always; this is a big concept in the Torah and it is the reason for the exaltedness of the Tzaddikim who walk before G-d..."
Both the Be'er Heitev and Mishna Berura explain as follows. A person should be aware that he is in the constant presence of The Creator, for the Holy One blessed be He fills the entire creation. A person should picture the letters Yod (and) Heh (and) Vav (and) Heh in front of his eyes with the same vowelization as the word yirah (fear). This is the real meaning of "I place Hashem before me always", and this practice has a great benefit in helping one gain fear of Hashem (fear of sin). The source given for this is in the writings of the Ari Z"L.
I was once learning this halacha in kollel and a gentleman sitting next to me who overheard this, shared an incredible story with me. He said that he had a secular nephew who after completing his duty in the Israeli army went off to India to experiment with meditation and spirituality. He found a group that was about to begin some sort of meditation and he joined in with them. They all sat in a circle and were given instructions of what to meditate on. This young man felt guilty about thinking of such unholy things and instead, an image of the name of Hashem popped into his head (he had grown up seeing a framed picture of a menorah in his house with the name of Hashem written on the top of it, so it was easy for him to picture it in his mind). A few minutes into the meditation, the group leader walked over to him and threw him out of the circle. Being determined to experience some spirituality, he went and found another meditation group. Again he was instructed on what to meditate on, and again he began to picture the name of Hashem. A few minutes later, the same thing happened and he was removed from the group again. He realized that this was not a coincidence, and he immediately returned to Eretz Yisrael and checked himself into a yeshiva where he began learnig Torah and eventually went on to become religious.
Attached above is an image of the name of Hashem with the vowelization of yirah (as mentioned in the Be'er Heitev and Mishna Berura)
Try looking at it for a few minutes, and see if you are able to picture the four letters in your head with your eyes closed. It could take some practice, but it comes with many benefits.
As a young child, the Rebbe (Rebbe Nachman) wanted to literally fulfill the verse, "I have set G-d before me constantly (Psalms 16:8)." He continually tried to depict G-d's ineffable Name before his eyes, even while studying with his tutor. His thoughts were so occupied that he often did not know his lessons, making his teacher very angry.
Despite this, the Rebbe acted like a normal child his age, playing, jumping and taking walks. But he was also very constant in the above practice.
(Shevachay HaRan #2)