By exploring your inner world.
This can be done through a number of different methods. Yoga (not just the stretchy western style), meditation, psychotherapy, art/being creative, trusting your own intuition, self-inquiry and many more. The inner senses are like muscles...they need to be used and trained to be effective. The more effective they are, the more you can trust the info they offer you. The more you trust them, the more you will use them. The more you use them, the better you will know yourself.
It's a learning process just like when you learn to play a musical instrument, with the difference that in our case, YOU are the instrument.
No mumbo jumbo here, but a very practical and logical approach to what people call spirituality.