With upcoming missions like the James Webb Space Telescope, we soon will be on the verge of detecting and characterizing Earth-like exoplanetary atmospheres around cool stars. However, recent observations showed that their radiation environment might be much harsher than that of the Sun. Thus, exoplanets in potentially habitable zones are most likely exposed to an enhanced stellar radiation environment, which could affect their habitability, for example, in the form of a hazardous flux of energetic particles. Knowing the stellar radiation field and modeling radiation exposure on a planet’s surface is crucial to assess its habitability. In this study, we present 3D magnetohydrodynamic-based model efforts investigating the astrospheres of three diverse M-star astrospheres and provide numerical estimates of the modulation of galactic cosmic rays (GCRs) within. We show that the impact of GCRs on the Earth-like exoplanets cannot always be neglected in the context of exoplanetary habitability.