  We present results from the volume-complete spectroscopic survey of
0.1-0.3M$_\odot$ M dwarfs within 15pc. This work discusses the active sample
without close binary companions, providing a comprehensive picture of these 123
stars with H${\alpha}$ emission stronger than -1$\unicode{xC5}$. Our analysis
includes rotation periods (including 31 new measurements), H${\alpha}$
equivalent widths, rotational broadening, inclinations, and radial velocities,
determined using high-resolution, multi-epoch spectroscopic data from the TRES
and CHIRON spectrographs supplemented by photometry from TESS and MEarth. Using
this volume-complete sample, we establish that the majority of active, low-mass
M dwarfs are very rapid rotators: specifically, 74$\pm$4% have rotation periods
shorter than 2 days, while 19$\pm$4% have intermediate rotation periods of 2-20
days, and the remaining 8$\pm$3% have periods longer than 20 days. Among the
latter group, we identify a population of stars with very high H${\alpha}$
emission, which we suggest is indicative of dramatic spindown as these stars
transition from the rapidly to slowly rotating modes. We are unable to
determine rotation periods for six stars and suggest that some of the stars
without measured rotation periods may be viewed pole-on, as such stars are
absent from the distribution of inclinations we measure; this lack
notwithstanding, we recover the expected isotropic distribution of spin axes.
Our spectroscopic and photometric data sets also allow us to investigate
activity-induced radial-velocity variability, which we show can be estimated as
the product of rotational broadening and the photometric amplitude of spot
modulation.
