Physical Benefits:

1.lower pulse rate
2.lower blood pressure
3.sense of relaxation-known as the relaxation response or stress relief
4.slower breath rate

Mental Benefits:

1.person get more control over his life by gaining control over his mind and senses.
2.person becomes more aware of his true identity as a spiritual being and not as his identification such
as his body, job, race, religion etc.
3.a person gets more in tune with his true identity and with the oversoul, universal energy, supreme truth ,Lord or
whatever term you would like to use.
4. inner peacefulness-stress relief
5.Regular practice of the mantra meditation systematically unfolds one's full potential: enlivening the inner intelligence
,developing higher states of consciousness,allowing a person to develope his inherent consciousness while cutting away
false indentifications.
This experience of the self-referral state enlivens orderliness, dynamism, and creativity within the meditator resulting in
greater effectiveness and success in daily life. This is explained in the Sanskrit vedas available here in the "Bhagavad-Gita, As It Is."