The first thing is to remove all trace of self-interest from your service of G‑d. But this requires profound insight, and you must keep it constantly in mind. For it is lost in a moment of inattention. The second important thing is regular immersion in a mikvah, keeping in mind the proper mystical intentions. The third thing is to avoid depression. You heart should always be happy in G‑d. Indeed, “a threefold cord is not quickly broken” (Ecclesiastes 4:12). Tzava’as HaRivash, p. 3a