Wu wei (simplified Chinese: 无为; traditional Chinese: 無爲; pinyin: wúwéi) is an important concept of Taoism (Daoism), that involves knowing when to act and when not to act. Another perspective to this is that "Wu Wei" means natural action - as planets revolve around the sun, they "do" this revolving, but without "doing" it; or as trees grow, they "do", but without "doing". Thus knowing when (and how) to act is not knowledge in the sense that one would think "now" is the right time to do "this", but rather just doing it, doing the natural thing.
Wu may be translated as not have or without; Wei may be translated as do, act, serve as, govern or effort. The literal meaning of Wu Wei is "without action" and is often included in the paradox wei wu wei: "action without action" or "effortless doing". The practice of wu wei and the efficacy of wei wu wei are fundamental tenets in Chinese thought and have been mostly emphasized by the Taoist school. The aim of wu wei is to achieve a state of perfect equilibrium, or alignment with the Tao, and, as a result, obtain an irresistible form of "soft and invisible" power.
There is another less commonly referenced sense of wu wei; "action that does not involve struggle or excessive effort". In this instance, Wu means "without" and Wei means "effort". The concept of "effortless action" is a part of Taoist Internal martial arts such as T'ai chi ch'uan, Baguazhang and Xing Yi. It follows that Wu wei complies with the main feature and distinguishing characteristic of Taoism, that of being natural. To apply wu wei to any situation is to take natural action.
'Effort' perhaps also relates to thought. For me, it's the thinking that can kill the doing of creativity.
What is 'natural action' in relation to painting, or taking photographs, or playing the mandolin? For me it's a response that attempts to be as direct as possible, with as little interference from thought as I can manage to allow.