The best way to cleanse the heart and prepare for the stilling of the mind is to lead a normal, worldly life. Living in the midst of your day-to-day duties, responsibilities, likes, dislikes, etc. , will help you. All these become the very means for the purification of your heart.
I liked the military life. They teach you self-sufficiency early on. I always say that I learned most of what I know about leadership in the Marine Corps. Certain basic principles stay with you - sometimes consciously, mostly unconsciously.