Your anterior core can never be strong enough. For the core-engaged dead bug, lie on your back with the hips and knees flexed to 90 degrees, and then pull a light band over your core/torso to engage the abs.
Exhale hard to get the ribs down, and think about "rolling" the pelvis back. Your back should be flat and pressed into the ground. From this position simply extend the hip and knee, focusing on keeping the back flat throughout.
The last time it happened I was getting changed in the locker room at my gym. Two pudgy-bellied gym members (PBGMs) were discussing the relative virtues and drawbacks of doing cardio as part of their training program.
We dug through the Author's Locker Room and found information gold in them-there hills. So with mule, shovel, and pick ax, we excavated the biggest, best nuggets from Thibaudeau mountain and melted them together to make this bright, shiny article.