The existence of Bhagavad Gita in Mahabharata itself is because of lack of decision making when Arjuna was overpowered
by his negative emotions and he was not able to take right decisions due to lack of right vision. His vision was clouded with fear, attachment and despondency. At that time what Lord Krishna taught is the most efficient counseling done by any Management Guru ever in infinite time. The timeless poetry from the mouth of Lord is although the part of the Mahabharata, but is considered as self sufficient Upanishad in itself.
Gita stresses on taming mind for better control over our actions as per Dharma. Mind is one such tool given to mankind free of cost by nature but is worthy of a life time wealth. A crystal clear mind helps one to take better decisions in life leading to all types of success at personal, professional and offcourse spiritual front.