  We propose a physically motivated parametrization for the unpolarized
generalized parton distributions. At zero value of the skewness variable,
$\zeta$, the parametrization is constrained by simultaneously fitting the
experimental data on both the nucleon elastic form factors and the deep
inelastic structure functions. A rich phenomenology can be addressed based on
this parametrization. In particular, we track the behavior of the average: {\it
i)} interparton distances as a function of the momentum fraction, $X$, {\it
ii)} $X$ as a function of the four-momentum transfer, $t$; and {\it iii)} the
intrinsic transverse momentum $k_\perp$ as a function of $X$. We discuss the
extension of our parametrization to $\zeta \neq 0$ where additional constraints
are provided by higher moments of the generalized parton distributions obtained
from {\it ab initio} lattice QCD calculations.
