Really?

Sitting on deck 12, I am watching two establishments, a cash and carry and a Crossfit training centre.
Right in the doorway so the world and its mother can see him, is a young man exercising. He has two dumbbells and is doing the classic, sqwat, swing up, raise dumbbells above head, routine.
He is doing it very, very badly; without a straight spine he reaches over and using the lumbar section, swings the obviously too heavy weights, up. The lumbar region of his back does well but is at maximum strain when the weights reach waist height, so now he braces, gives a little bounce, and still using the lumbar and the shoulder rotator muscles, to swing them the rest of the way. Mm.
A woman comes out of the Cash and Carry with a trolley stacked with boxes. She undoes her car and with straight back, opens doors in readiness. Bending her knees and holding her back firm and straight, she lifts up the heavy boxes and leavering them high enough to walk comfortably to the car, she strides over, and places them in the boot. No stain, no fluster, over and over she repeats this exercise, working hard and mentally keeping a close watch on her under five-year old son.
At the end of 5 repeats, the young man wipes his brow and looks about probably for approval.
After 10 or more repeats the woman reaches out her hand and she and her little boy walk the trolley back to the trolley bay.
I rest my case and if you dont get it, think about it.
Do you really need the gym to get fit?