  We present an analytic model for how momentum deposition from stellar
feedback simultaneously regulates star formation and drives outflows in a
turbulent interstellar medium (ISM). Because the ISM is turbulent, a given
patch of ISM exhibits sub-patches with a range of surface densities. The
high-density patches are 'pushed' by feedback, thereby driving turbulence and
self-regulating local star formation. Sufficiently low-density patches,
however, are accelerated to above the escape velocity before the region can
self-adjust and are thus vented as outflows. In the
turbulent-pressure-supported regime, when the gas fraction is $\gtrsim 0.3$,
the ratio of the turbulent velocity dispersion to the circular velocity is
sufficiently high that at any given time, of order half of the ISM has surface
density less than the critical value and thus can be blown out on a dynamical
time. The resulting outflows have a mass-loading factor ($\eta \equiv M_{\rm
out}/M_{\star}$) that is inversely proportional to the gas fraction times the
circular velocity. At low gas fractions, the star formation rate needed for
local self-regulation, and corresponding turbulent Mach number, decline
rapidly; the ISM is 'smoother', and it is actually more difficult to drive
winds with large mass-loading factors. Crucially, our model predicts that
stellar-feedback-driven outflows should be suppressed at $z \lesssim 1$ in
$M_{\star} \gtrsim 10^{10} M_{\odot}$ galaxies. This mechanism allows massive
galaxies to exhibit violent outflows at high redshifts and then 'shut down'
those outflows at late times, thereby enabling the formation of a smooth,
extended thin stellar disk. We provide simple fitting functions for $\eta$ that
should be useful for sub-resolution and semi-analytic models. [abridged]
