From Dovid Sears, “The Path of the Baal Shem Tov” (Jason Aronson).
The Baal Shem Tov on Secluded Meditation:
How can one merit to cleave to God? By secluding oneself (hisbodedus) from one’s fellow men, by writing the mysteries of the Torah, and by meditating on the kabbalistic unifications (yichudim) of the Arizal (Rabbi Yitzchak Luria), as is known. When one engages in such unifications, he should remain aware of God’s greatness [and not be distracted by the techniques themselves] to the best of his ability (Tzava’as HaRivash 82).