Real Dictionary

exercise
verb: If you exercise something such as your authority, your rights, or a good quality, you use it or put it into effect.

exercise in American English
active use or operation; employment
intransitive verb: to go through exercises; take bodily exercise
noun: bodily or mental exertion, esp. for the sake of training or improvement of health
transitive verb: to put through exercises, or forms of practice or exertion, designed to train, develop, condition, or the like

exercise in British English
to put into use; employ
noun: physical exertion, esp for the purpose of development, training, or keeping fit