This chapter discusses getting introduced to physiology of work and play, which often involve locomotor activity. Locomotion is achieved by skeletal muscles, so called because they are attached to bones, and bring about movement at joints. A nerve is a bundle of nerve fibres. The part of the neuron which has the nucleus is called the cell body. Motor neurons are subject to at least a dozen influences, some excitatory and some inhibitory. The voluntary influence on muscles originates in the cerebral cortex, the seat of all conscious activity in the brain. Voluntary muscles are under the control of will power, but not under the control of will power only. All muscular movement results from contraction. Force, multiplied by the distance over which it works, is called work. Work for recreation is called play. Skeletal muscles engage in work or play, depending on their owner’s will and outlook. Keywords: inducing contraction, pumping action, amoeboid movement, enzymatic mechanisms, homeostasis, biological phenomenon, professional players, complex systems, accommodation, physiological function, paralysed individuals, skeletal muscles, voluntary influence, protein synthesis, contractile elements, muscular movement, and internal environment.