Effort: easy. The smallest step there is. You barely leave missionary.
From missionary: she raises her hips for a moment, you slide the pillow under, and she settles back down.
Pillow: low under her hips, with her legs relaxed and straight.
Why it's easier: her hips rest a little higher on firm foam. Nobody has to hold the change by effort.
Try it if: you want something new tonight without learning anything new.

