Here God Krishna is saying to Arjuna that to be in pure transcendental consciousness, a person must give up all the varieties of sense gratifications which arise from the engagement of senses as per direction of mind which is not stable, fickle and wandering here and there and which is the friend and enemy of a person.

Text 57, Book: Bhagavad-Gita As it Is, page 131, Chapter 2: Contents of Gita Summarized.
In the material world, one who is unaffected by whatever good or evil he may obtain, neither praising it nor despising it, is firmly fixed in perfect knowledge.

Chapter 2 Text 55:The Supreme Personality of Godhead said: O Pārtha, when a man gives up all varieties of desire for sense gratification, which arise from mental concoction, and when his mind, thus purified, finds satisfaction in the self alone, then he is said to be in pure transcendental consciousness.

The mind is our friend if we can control it and the mind is our enemy if we allow ourselves to be controlled by it. These urges for the satisfaction of material sense gratification arise because of the tendency of mental concoction in us which make us believe something which is not true.

It is just like if we add different ingredients in a new way to make some new meal. Our mind creates a mental concoction as it picks some part of the story from somewhere and remaining parts from some other stories and presents a new picture in front of us which appears to be astonishing but in reality, the new picture is far from reality however fascinating it may appear to us. The mind keeps us in agony, stress, anxieties, worries for events that will never happen in our life. It keeps us fearful for our future. The main thing to fear is fear itself. When we take shelter of Krishna only then we can have peace and bliss and rest is material energy which has a strategic plan to perpetuate our pains, worries, anxieties continuously by keeping us in fear which is agent of material energy. Material energy keeps us in fear of disease, old age, death, losing our employment, hunger, poverty, shelter so we work so hard day and night from eight hours to twelve hours and sometimes more than that due to fear of unemployment, hunger, poverty and suffering all kinds of stress, worry, pain, insult, humiliation at the workplace. 

Text 58, Book: Bhagavad-Gita As it Is, page 132, Chapter 2: Contents of Gita Summarized.
One who can withdraw his senses from sense objects, as the tortoise draws its limbs within the shell, is firmly fixed in perfect consciousness.

Text 59, Book: Bhagavad-Gita As it Is, page 132, Chapter 2: Contents of Gita Summarized.?Though the embodied soul may be restricted from the sense enjoyment, the taste for sense objects remains. But, ceasing such engagements by experiencing a higher taste, he is fixed in consciousness?.

This higher taster is Krishna Consciousness in which we do devotional service to God Shri Krishna. We will get as per our destiny which is formed before our birth as per our pious and impious actions in previous births. There is no need to run for material success as we will not be able to get more than what is destined for us irrespective of our hard work and efforts. We have to keep our focus on the worship of God Shri Krishna and render devotional service to God Shri Krishna to get freedom from the cycle of repeated birth and death, old age, diseases and this dangerous material world full of miseries, worries, anxieties, pain and which is not our real home as our real home is Golok Vrindavan or spiritual sky. One who reaches there after death never returns to this miserable and dangerous material world.

Respected obeisances unto my spiritual master and God Shri Krishna.

Hare Krishna.

Pankaj Mannan