In this paper, we provide insight into understanding living system negative entropy growth and repair processes from a thermodynamic perspective. Living systems are viewed as cyclic from a daily perspective of work, sleep, nutritional consumption, waste, breathing, growth, and repair cycles. We assess growth and repair with an equivalency cyclic work model. In a repair, for example, the free energy of the system is restored close to the original state with some imperfect repair that also occurs. We illustrate this using an equivalent amount of cyclic work by comparing it to a heat engine and assessing its efficiency. Results of modeling suggest a type of living system heat engine and cyclic efficiency that we were able to compare to a Carnot type efficiency for repair and growth processes that are insightful in the thermodynamic framework compared to traditional medical methods. The efficiency is somewhat paradoxical in Second Law treatment as one might expect due to the spontaneous negative entropy nature of growth and repair in living systems compared to the spontaneous entropy nature of disorder in passive systems. We suggest a simple modification of the Second Law in negative entropy terms. We also suggest metrics that can be used to assess a living system’s ability to generate negative entropy using the fractional repair and a repair rate function that is comparable to an electric RC circuit charge-discharge model. Results provide new insights on how to approach living system negative entropy thermodynamics.