We analyse a simple, deterministic queueing system with feedback. We model a customer's decision to seek service as a two-stage process: (1) deciding whether or not to use a facility (become a customer), and (2) deciding the frequency of use (daily, weekly, monthly, etc.). We consider both a constant and a deterministic, time-dependent usage pattern. We ignore variability, and focus on three forms of feedback: (1) the service rate increases as queue length increases; (2) the frequency with which customers use the service depends on customers' perception of recent waiting times; and (3) the number of customers depends on their perception of long-term average waiting time. Although highly stylised, this model captures the essential features of many real-life systems whose average arrival rate varies over time. The main conclusions are that more capacity can make the system less manageable, and a stronger external cycle can be a stabilising factor. The model turns out to be remarkably robust to external disturbances.