Can you share your "illustrated guide to back exercises, aka core strength exercises" ?
The hardest one for me is lying face down, arms extended forward. Lift your chest and legs off the ground. Oww! These are called "Supermans" because you look like Superman flying through the air.
It'll give you a vast new appreciation for when a dancer lifts his partner overhead by the waist and she gracefully lies prone only supported by his hands on her waist.
I double-dare you to even get your hands an inch off the ground!