What Is a Mantra /Affirmation and How Does It Work?
Mantra repetition is an ancient meditation technique  extensively used in Tibet and India. What actually is a mantra  Mantra repetition simply means  repeating a sentence or group of words that have a phonetic significance. Just that’s it.Mantra is intrinsically related to sound. Mantra is sound, and sound is reverberating in everything in this universe. When water flows, the gurgling sound it makes, is mantra. When wind blows through the trees, the  rustling sound it produces is mantra.  When we walk on the earth, our footsteps produce sound, and that too is mantra. Within  human beings  there is a self-born, indestructible sound which repeats itself constantly, along with our breathing and this sound is also a mantra. Sound has enormous power, in fact it has the power to create an entire universe. It is written that God originally manifested as sound. 

(In the beginning was the Word, and the Word was with God, and the Word was God.  New Testament, John1:1-2 ) According to ancient Indian belief  in the beginning there was sound, which  reverberated as Om and from that sound everything came into existence. Even modern scientist are beginning to recognize as our ancient sages did,  that there exists a vibration which reverberates ceaselessly throughout the cosmos. When letters and syllables come together, they form words. Both our spiritual and our mundane life are possible only because of words; without language, we can not carry out any of our activities. Each word we use has its own power and produces it own reaction. A mantra is no ordinary combination of letters and syllables, but a living force. The name of God is not different from God. Mantra has been called the sound-body of God: It is God in the form of sound. In  Bhagavad Gita Lord Krishna says, ” Among rituals, I am the ritual of mantra repetition.” By this he means that while other techniques are means of attaining Him, mantra is his very being. That is why it is so easy to experience God by repeating the mantra. Mantra meditation is the repetition of a group of words which create  sound vibrations that awake the love of God in our hearts and mind.
Source: meditationiseasy.com

“Prana” is a Sanskrit term for a form of life energy which can be transferred from individual to individual. Prana may or may not produce an instant dramatic effect upon transfer. There can be heat or coolness as a result of the transfer. Some healers operate through transfer of prana. A massage therapist can transfer prana with beneficial effect. Even self-healing can be accomplished by concentrating prana in certain organs, the result of which can be a clearing of the difficulty or condition. For instance, by saying a certain mantra while visualizing an internal organ bathed in light, the specific power of the mantra can become concentrated there with great beneficial effect.Mantras eventually quiet the mind. At a deep level, subconscious mind is a collective consciousness of all the forms of primitive consciousnesses which exist throughout the physical and subtle bodies. The dedicated use of mantra can dig into subconscious crystallized thoughts stored in the organs and glands and transform these bodily parts into repositories of peace. Source: http://www.sanskritmantra.com/what.htm

Self-Healing / Mantra / Affirmation
“My Body is a Temple of Divine Life and Energy, I am Healthy and Whole.”
by Dr. Caroll Penn and Guru6

Consciousness Mantra / Affirmation
“Living in the Presence of God,
Truth is One and Eternal, Realize Oneness with it, in Your Deathless Self Within.”
From Rays of the One Light by Paramahansa Yogananda  
Soundtrack by Guru6