From Objectivism Wiki
"My philosophy, in essence, is the concept of man as a heroic being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute."
Like for all living being, continued survival for man requires a continuous effort to gain the values necessary for his life: food, water, shelter, and every other comfort that aids man in his life. Furthermore, man is born as a self-contained being, possessing the primary means necessary for his survival: his mind to choose the means by which to ensure his continued survival, and his body to act on those choices. Unlike animals, which are guided by instinct and have no such choice, man's primary choice in life is to act towards his life, or if he does not, to act towards his death. The primary means of man's survival is his mind, which he must use to choose the means and values that are necessary to sustain his life.
Since the nature of reality determines the material values man needs to sustain his life, the facts of reality also determine which actions man must take to gain those values. Man cannot achieve these material values by acting randomly: he can only ensure his continued survival by a consistent and continual effort to achieve the values needed for his life. In order for this effort to achieve the desired results, man must respect his nature are a physical, living, rational being as well as the nature of reality and the actions he must take to gain the values he desires from the rest of the universe. In short, to make living in accordance with his nature as a rational human being a constant part of his life, man must hold and live by certain values. (A value is something that you act to gain or keep. -- Ayn Rand) Supreme among these values is reason, the means by which man determines all his other values. Secondary, are the values of purpose and self-esteem. Together, the values reason, purpose, and self-esteem allow man to realize his ultimate value: his life.
To act on his values, man must translate these values into virtues by which to guide his actions. (A virtue is "the action by which one gains and keeps a value." -- Ayn Rand)
The virtues on which the primary values depend are rationality, productivity, and independence. The man who is successful in living is able to derive the values necessary for his life and to translate them into the virtues necessary to gain and keep them. Some skeptics might say that this is a "cold, unemotional, and rationalistic" way to go about life, but nothing can be further from the truth. The man who confidently acts to achieve the values necessary for his life knows that it is his life he is acting to further, and that it is his values that he is achieving. The emotional state of knowing that one is an effectual, capable, productive individual who is master of his own destiny is self-esteem. Self-esteem is the confidence one has in his own worth as a human being and his ability to achieve his values. When a man makes the achievement of his values a way of life, happiness is that state of consciousness that results. Thus, the rational, productive, and self-confident man and woman know the value of their life and takes pride in their achievements.