Stellar age is a key fundamental property, but is extremely difficult to measure for individual stars. Low-mass stars, or M dwarfs, are the most numerous stars in the Galaxy, and are likely to host the majority of Earth-like exoplanets. For this reason, these main sequence stars are ideal for studying the Milky Way and exoplanet properties. However, ages of M dwarfs are especially difficult to estimate because methods used for solar-type stars break down as lower mass objects become fully convective. Empirical and statistical methods are required to constrain the ages of M dwarfs. Given that M dwarfs evolve slowly with time, inferring their ages requires taking into account several age indicators together, for example: 1) Position in the color-magnitude diagram; 2) Magnetic activity, as indicated by the H-alpha emission line; 3) Full kinematics, taking advantage of Gaia DR2 and DR3; 4) Rotation periods. I will present the age-calibrations I did of these age indicators, including the age-activity relation for the H-alpha emission line. I will show the empirical age-activity relation I obtained, which indicates that H-alpha equivalent widths decrease with age. I will also show how these age indicators can be used to estimate M dwarf ages, and what are the steps to improve its precision in the future.