I develop a simple model of precautionary behavior in the context of avoiding an infectious disease. I show that in an infinite horizon model, the degree of caution is always nonmonotone in the discount factor; in extensions with finite number of periods or stochastic termination, the degree of caution is nonmonotone with sufficient number of periods or sufficiently low termination probability. I extend the model to allow interaction between agents using the SIR approach. I find that again, precautionary behavior is not monotone in the discount factor. With high discount factors, individual precautionary behaviors are strategic complements.