Do you work your "Y"? Well you should...it is an easy way to feel connected to your "core." The "Y" connects your armpits to your belly button, and then your pelvic floor (like a kagel) pulling up toward your navel. Feeling these points connected gets your external obliques to work so your rib cage stays aligned over your pelvis. Engaging the pelvic floor stabilizes the lower part of the pelvis. All the energy meets at your navel activating your deep abs. Your upper body is now all connected.
I find this "Y" visual helpful for quickly getting into my core and stabilizing my torso while doing a bunch of different activities, from hauling toddlers around to doing free weights I use the "Y" to keep my torso still when doing bi-cep curls. It totally helps get rid of the "sway back into the heels" that often accompanies the lift. Try the "Y" when you do your next set of push-ups - keeping your torso all trussed up really helps out your arms as they push your entire body weight away from the floor.
So use your "Y" - practice it while standing in line for your morning latte.
If you have some questions about your core read this post Core Questions and hopefully it will answer yours.