  We generalize the worldline variational approach to field theory by
introducing a trial action which allows for anisotropic terms to be induced by
external 4-momenta of Green's functions. By solving the ensuing variational
equations numerically we demonstrate that within the (quenched) scalar
Wick-Cutkosky model considerable improvement can be achieved over results
obtained previously with isotropic actions. In particular, the critical
coupling associated with the instability of the model is lowered, in accordance
with expectations from Baym's proof of the instability in the unquenched
theory. The physical picture associated with a different quantum mechanical
motion of the dressed particle along and perpendicular to its classical
momentum is discussed. Indeed, we find that for large couplings the dressed
particle is strongly distorted in the direction of its four-momentum. In
addition, we obtain an exact relation between the renormalized coupling of the
theory and the propagator. Along the way we introduce new and efficient methods
to evaluate the averages needed in the variational approach and apply them to
the calculation of the 2-point function.
