  Magnetic activity and rotation are related to the age of low-mass main
sequence stars. To further constrain these relations, we study a sample of 574
main sequence stars members of common proper motion pairs with white dwarfs,
identified thanks to Gaia astrometry. We use the white dwarfs as age
indicators, while the activity indexes and rotational velocities are obtained
from the main sequence companions using standard procedures. We find that stars
older than 5 Gyr do not display Halpha nor Caii H&K emission unless they are
fast rotators due to tidal locking from the presence of unseen companions and
that the rotational velocities tend to decrease over time, thus supporting the
so-called gyrochronology. However, we also find moderately old stars (~2-6 Gyr)
that are active presumably because they rotate faster than they should for
their given ages. This indicates that they may be suffering from weakened
magnetic braking or that they possibly evolved through wind accretion processes
in the past. The activity fractions that we measure for all stars younger than
5 Gyr range between ~10-40 per cent. This is line with the expectations, since
our sample is composed of F, G, K and early M stars, which are thought to have
short (<2 Gyr) activity lifetimes. Finally, we observe that the Halpha
fractional luminosities and the R'HK indexes for our sample of (slowly
rotating) stars show a spread (-4>log(LHalpha/Lbol); log(R'HK)> -5) typically
found in inactive M stars or weakly active/inactive F, G, K stars.
