One of the most powerful spiritual practices I know is introspection. Going within, paying attention to what I am feeling, to the trend of my thoughts, even to my physical sensations, and especially to that still small voice, allows me to know.
Being still, and knowing, then allows me to make decisions I can trust, and take actions that serve my highest good.
Without this practice, I would be lost. Done alone, this practice is invaluable. Done in conjunction with meditation, it packs a power punch that has served me very well for a long time.