"People often say: “I can deal with things on the physical plane, but on the astral and mental I can do very little; it is so difficult.” That is the reverse of the truth. They are not accustomed to thinking and working in that finer matter, and so they believe that they cannot. But as soon as their will is set, they will find that things will follow the direction of that will in a way impossible in the physical world."
January 1, 1970
https://en.wikiquote.org/wiki/Masters_of_Wisdom_(Theosophy)