Simulation environments have proven to be very useful as testbeds for reinforcement learning (RL) algorithms. For settings where an actual human user is involved, these simulation environments allow one to test out the suitability of new RL approaches without having to include real users at first. It obviously does require the simulator to have a certain degree of realism, however, realistic simulators for the behavior of humans in the health domain are rarely seen. To generate realistic behavior, the simulator could be driven by data from real users, but this might lead to privacy issues. In this paper, we propose to use Generative Adversarial Networks (GANs) for generating realistic simulation environments. In this first step, we use an existing simulator that simulates daily activities of users and the GANs are used to generate realistic sensory data that accompanies such activities. After training, the original (potentially privacy sensitive) data can be thrown away and the simulator can simply be driven by the GAN models. Results show that a model trained on real data shows similar performance on the data artificially generated by the GAN.