Totally agree about looking after your core. I have always been fit, strong and active and never used to give a second thought about lifting, wearing heavy basses or anything physical - always a bit proud of my strength, to be honest. Carried a coupe of extra stones in weight, never a problem.
Then my back went. A series of sacro-iliac problems and, last year, a prolapsed disc leading to sciatica.
Everything changes. Everything - it impinges on ALL aspects of your life. From how you sit on the toilet to what shoes you wear. Core excercise is THE only way to manage it. Doesn't matter how fit you think you are, it is only when you target your TVA muscle that you realise it exists! Lightweight clobber is just one small piece of the complicated jig-saw of mobility.