The presence of a large global planetary field acts as a probe deep into the planet. It informs us of the planet’s internal structure, dynamics, and thermal evolution, and provides a limit on the rapid hydrodynamic escape of the planet's atmosphere. For habitable zone planets like the Earth, the field acts as a critical shield against cosmic rays and high-energy stellar particles which would otherwise damage both the atmosphere and biosphere. We have so far detected several planetary magnetic fields by observing magnetic interactions between a star and its closely orbiting giant planet. We are extending our star-planet interaction techniques from ''hot Jupiters'' around Sun-like stars to rocky planets in the habitable zones of low-mass stars. This will allow us to study the atmospheric conditions and potential habitability of these ubiquitous planets. Intense UV exposure may also affect potential biosignatures and the production of hazes, interfering with the study of planetary atmospheres. Our work on the UV exposure and magnetic fields of exoplanets will identify planets that have most-likely retained their atmospheres and been unaffected by hazes. These will become the best planetary targets for atmospheric characterization by the upcoming James Webb Space Telescope and extremely large ground-based telescopes, such as the Giant Magellan and Thirty Meter Telescopes. Lastly, such studies of low-mass stars and their habitable zone planets provide a critical science case for future UV space telescopes.