From Dovid Sears, “The Path of the Baal Shem Tov” (Jason Aronson), pp. 47-49. Footnotes have been omitted for this online version.
“I have placed (shivisi) God before myself continually” (Tehillim 16:8). “I have placed (shivisi)” is related to the word hishtavus, equanimity. Whatever happens to a person should be the same to him, whether others praise or disparage him; and this rule applies to all things. When it comes to eating, it should make no difference whether one eats tasty foods or otherwise. Everything should be the same to him, since the Evil Inclination has been completely renounced. In all circumstances one should say, “Does this not come from Him, may He be blessed? And if this is meet and proper in His eyes, [should it not be acceptable to me?]” One's efforts should be entirely for the sake of Heaven; but [whatever happens] should make no difference from one's own standpoint. This is a very high spiritual level (Tzava'as HaRivash 2).
The Baal Shem Tov stressed the great importance of equanimity (hishtavus). That is, it should make no difference whether one is taken to be an ignoramus or an accomplished Torah scholar. This may be attained by continually cleaving to the Creator-for due to his deveykus, there is no possibility for a person to consider [what other people think]. Rather, he should continually endeavor to attach himself Above to God, may He be blessed (Tzava’as HaRivash 10).
One should think of himself as belonging to the Upper World; then all those who dwell in this lower world will make no impression upon him. For this whole world is like a mustard seed in comparison to the Upper World. The love or hatred of others should be the same to him, for it amounts to nothing.
Likewise, one should not heed in the least the desires of one's impure body, which the Tikkunei Zohar (Tikkun 21, 48b) compares to the leprous skin of a snake (Tzava’as HaRivash 6).
One should make himself as if he does not exist, as the Gemara states, “Rabbi Yochanan taught: The words of Torah cannot be fulfilled except by one who makes himself as if he does not exist. Thus the verse states, ‘And wisdom -- from where (ayin) does it come?’ [Or, alternatively, ‘And wisdom comes from Nothingness (ayin).’]”
This means that one should think that he does not exist in this world at all -- so what difference does it make if he is important in the eyes of others? (Tzava’as HaRivash 53).
When one speaks words of Torah with others, he should first bind himself in thought to the Creator, may He be blessed. [He should also contemplate that] the soul of his fellow is similarly bound to the Creator, for all men live only because of the shefa (abundance) which God imparts to all creatures.
One should think, “I am speaking only before the Creator, may He be blessed, in order to gratify Him. I am not performing for my fellow men -- for what difference does their praise or blame make to me?” (Tzava'as HaRivash 93).
In everything one does, his only purpose should be to gratify the Creator, and not to serve himself in the least. Even the desire to experience delight in the act of Divine service is a form of serving oneself (Tzava'as HaRivash 11).
The Gemara states: “Many attempted to conduct themselves like Rabbi Shimon bar Yochai but were not successful” (Berachos 35b). This means to say that they wanted to mortify themselves in order to reach the spiritual level of Rabbi Shimon bar Yochai, and that is why they were not successful. One's only intent in Divine service should be to gratify the Creator alone, not to attain a lofty spiritual level (Tzava'as HaRivash 47).