MANTRA

Every mantra contains within its vibration  certain power. Upon concentration and repetition of a specific mantra, its energy is liberated and spreads through out. There are different types of mantras. Some called Bija (Seed) mantra. They have no exact meaning but act directly on the nerves of astral body. The other type of mantras, having a combination of words, and having some meaning also set up powerful vibrations in the body. Most common, however is the deity mantras, in which a specific form with attributes is visualized along with the repetition of the sound. start repeating it  mentally with faith and devotion everyday Please pronounce the mantra properly to avoid any negative effect.
Examples of Bija mantra:
AUM
SHRIM
GHAM
AIM .... etc.
And among these common is AUM...normally missunderstood as OM.You can have more info on this Bija mantra here.
similarly each bija mantra has impact on certain parts of our body meaning to say glands..or according to indian system the 'Chakras' which are associated with endocrinde glands
Here is some:
Brow chakra called ANJNA-associated PITUITARY GLAND- Bija mantra AUM
Throat chakra called VISHUDDHI-associated  THYROID GLAND- Bija mantra HAM
Heart chakra called ANAHATHA- associated THYMUS-Bija mantra YAM

Now lets look at Deity mantra with a example, Very common mantra we hear is 'GAYATRI MANTRA'
OM BHUR BHUVA SUVAH
TAT SAVITHUR  VARENYAM
BHARGO DEVASYA DHEEMAHI
DHIYO YO NAH PRACHODAYATH.
Meaning OM -base sound
BHUR-Physical world
BHUVA-Mental world
SUVAH-Spiritual world
TAT-God
SAVITHUR-Sun
VARENYAM-Attractive
BHARGO-Bright ray of light
DEVASYA- Supreme Lord
DHEEMAHI-We meditate
DHIYO-Understanding
YO-May this light
NAH-Our
PRACHODAYATH-Guide.
 Its important to visualize the meaning of these mantra.... its another type of meditation. bringing body and mind together.
HAPPY CHANTING :)