From the perspective of traditional Buddhism, mindfulness is one of the Eightfold Paths of the Dharma. It means that in order to practice the Dharma, every thought should be fully aware, and the mind is not distracted in the present moment. The purpose of mindfulness is to integrate one’s body and mind in order to achieve an enlightened state of liberation. The methods of mindfulness include making bodhisattva wish and practicing serene contemplation and silent-illumination meditation. Hence, one may even reach the situation of letting go of all things. Since 1979, the Western society has borrowed the Buddhist concepts and methods of mindfulness to actively develop some programs concerning stress reduction and healing of mental illness (such as Mindfulness-Based Stress Reduction (MBSR), and Mindfulness-based Cognitive Therapy (MBCT) programs etc.). Through emphasizing living in the moment with non-judging and nonstriving attitude, MBSR and MBCT programs have obviously helped in reducing physical and mental stress and pain, as well as in the treatment of mental illness, so it is widely prevailing in the mainstream society in the West. This article first discusses the difference in meaning between mindfulness practice of traditional Buddhism and MBSR and MBCT programs, and then analyzes the impact of those on emotional balance. Finally, in the conclusion, from a cross-disciplinary perspective on Buddhism, three points of view are proposed in the study of mindfulness.