Starting problem

Im having trouble starting my 2012 vw jetta se.
Itll some times kick over if im lucky, or other times
itll just click rapidly.
But evwn when i do turn it over and get lucky, i
notice in the process, that my dash lights dim out
until the car is fully on.
Whats causing my lights to dim out like that?
My battery checks out good, and even on the
terminals as well.