Life is an activity to transform the world on the basis of knowing it. People's life activities can not be separated from the objective world and are restricted by objective natural conditions and social material living conditions. Without the external objective world, people cannot survive and develop. However, people have conscious initiative, and can gradually and deeply understand the nature and laws of the objective world in life practice, so as to consciously transform the objective world and create an environment and conditions conducive to people's survival and development. This is the fundamental difference between humans and animals. Animals only use the external nature, while human beings make nature serve their own purposes by transforming the objective world. Therefore, transforming the world is the purpose and destination of life activities. At the same time, in the process of understanding and transforming the objective world, people have also exercised and improved their ability to conquer nature, enjoyed the fun of creation, enriched and improved their lives, and promoted the progress and development of human society. 3. Life is the unity of material creation and spiritual creation. The content of life is very rich, and the field of life is very broad. But to sum up, it is nothing more than material creation activities and spiritual creation activities. The dialectical unity of these two aspects constitutes the complete content of life. Material creation is the first historical activity of life and the premise and foundation of life process. Without material creation, people can't leave the animal kingdom, society can't exist and develop, and there can't be a real life. Spiritual creation is a process of summarizing, generalizing and rising the experience of material production activities. The result of spiritual creation is the spiritual civilization of society, which is also the basic activity of human beings. Material creation activities and spiritual creation activities are interrelated and inseparable. Material creation activities are the premise and foundation of spiritual creation activities, and spiritual creation activities cannot be separated from material creation activities. On the other hand, spiritual creation has an important influence on material creation. Without the development of spiritual civilization and scientific culture brought by spiritual creation activities, material creation activities are blind and passive. It is the unity of material creation and spiritual creation that constitutes the basic content of human life and promotes the continuous enrichment and development of life. Contemporary college students have high knowledge level and strong thinking ability, and pursue a high-level spiritual life. They should actively hold material creation activities and constantly carry out spiritual creation activities, thus enriching their beautiful lives. 4. Life is the dialectical unity of subject activity and object activity. The subject of life refers to the basis of human life activities, that is, people themselves. The object of life is relative to the subject. It refers to the object of people's cognition and practical activities, including people themselves besides the external objective world in which people live. Because people have the dual identity of subject and object, life is a dialectical unity process of interaction between human activities as subject and human activities as object, and it is a process in which the subject knows and transforms the object and the object is known and transformed by the subject. It is in this process that people constantly abandon and transform the "old self" and shape and enrich the "new self", thus gradually moving towards a better life. In short, in essence, life is the dialectical unity of individual life activities and human social life, the dialectical unity of understanding the world and transforming the world, the dialectical unity of material creation activities and spiritual creation activities, and the dialectical unity of subject activities and object activities. The scientific outlook on life has four characteristics: distinct objectivity, inherent regularity, complex contradiction and enterprising dynamics, and it is a process of continuous improvement and development. It is an objective life choice for contemporary people to understand the essence and characteristics of life, devote themselves to the fiery practice of socialist modernization and reform and opening up, love life, enrich life and explore life.