Source via: YouTube
Watch the core video above and give it a go. Using your core is one of the best things you can do for your body, it not just improves your workouts but also improves your posture. Using your core helps you not get injury's, helps your posture and back stay strong in the movement and gives your body strength.
I have been learning aerials for over a year and core is so important. I am only just re-learning how to use my core and it is hard work.
Tuck in your stomach. Squeeze in your butt for a tight core. Now hold it in like this as long as you can (and still be able to breathe).
When walking, to improve your posture, tuck in your stomach and about 20% squeeze in your butt.
Give it a go and tell me how you feel. The first three days I struggled with it but then by day four, it didn't hurt so much. Yet, a few weeks in and I still have to remind myself to put in my core ALL the time.