The association of a star with the different galactic components determines on a first order its velocity within the Galaxy. This stellar motion influences the structure and dynamics of the ejected Asymptotic Giant Branch (AGB) envelope as the stellar mass loss interacts with the local interstellar medium (ISM). We have explore the effects that this relative movement has in the formation of asymmetries in AGB envelopes and planetary Nebulae (PNe) shells. Our models follow the wind modulations prescribed by stellar evolution calculations, and we cover a range of expected relative velocities (10–100 km/s), ISM densities, and stellar progenitor masses. We have also explored the influence of the ISM magnetic field. We show how and when bow shocks and cometary-like structures form, and in which regime the shells are subject to instabilities. Finally, we analyze the results of the simulations in terms of the different kinematical stellar populations expected in the Galaxy.