Three morning mantras, the Mahamrityunjaya mantra, Gayatri mantra and the 32 names of Durga, are the sankalpa mantras. They are enforcing an idea, they are enforcing a thought, a condition that you desire in life. They are trying to build a situation in your life according to your sankalpa.
These sankalpa mantras are repeated when you are mentally fresh, like early morning when you wake in that half sleeping and half-awake condition. Let them enter into your subconscious mind. The subconscious mind is the creative mind, the conscious mind is the interactive, sensorial mind, and the unconscious mind is loss of awareness, knowledge and perception. It is the subconscious mind which is responsible for mastery of life, mastery over mind, over habits and one’s nature, behaviour, traits, and the sensorial activity. It is the subconscious mind which trains you. Therefore, the sankalpas are put in the subconscious mind when the mind is in the state of relaxation.
Your personal mantra or guru mantra is according to your horoscope and zodiac sign. It indicates your own natural frequency and vibration. That mantra is practised at night when the mind is tense and agitated, when you come back from your involvement and interaction with society, the family and the world, when you are mentally exhausted and tired, then you do the guru mantra not when you are relaxed and peaceful. The guru mantra will bring the experience of balance, tranquillity, harmony, peace and happiness by disconnecting you from the influence of suffering and dejection. It makes you stable in your own nature.