An apparatus and method provide various desk structures as workstations to receive a user, standing or sitting, walking or stationary, exercising or sedentary. A double duty desk system may include multiple, dedicated “sitting desks” at seated height and fixed to a shared “standing desk,” the height of whose desktop stands accessible to a user exercising on an exercise bike, treadmill, stepper, or the like. A user in an exercise (e.g., standing) position may view materials set on the standing desk and on the attached sitting desks and returns. Heights of desks may be permanently fixed, adjustable, powered, mechanized, manual, or a combination. A user may selectively exercise or sit, in order to read, browse online, attend webinars, edit, monitor, handwrite, type, lecture, listen, answer phones, make calls, develop software, or the like from a standing or sitting position, at will.