Jesus Christ, it burns. Without thinking- without even being religious- I make the sign of the cross, crying out to be crucified, for the pain to be eased.

Six... seven...

Red-faced, hot-blooded, sweat beading my forehead like a necklace of honour, I throw down the dumbbell on my 8th repetition. Its thud synchronises with the beat drop of Toxic (who doesn't love a bit of Britney?), marking my triumph like the proud smile of my father when I let him know where I was going with our Matthew this morning.

"Have a great time, Joe!" He called after me as I shut the door. "And make sure to keep going until you can't lift any more!"

And so it was that my brother and I swaggered to our local gym, his forearms bursting from his long sleeve, mine looking like they could've been snapped off a tree branch by a naughty kid. I was convinced I could breeze through any set of exercises for hours.

It's been half an hour and I'm ready to go home to my dog.

Nonetheless, my set ended beautifully with that beat drop. I turn to Matthew.

"Your turn, yeah?"

He laughs. "Not quite. You can easily do four more."

"Four? Are you taking the piss? I barely managed six! My form went to shit on the last two!"

"Sometimes you have to sacrifice your lower back to reach true failure."

I gawk at Matthew, who grins, his cheeks puffed as if he's holding back a guffaw.

At last, I know his and Dad's secret, why they always moan about their backs being sore when they have to vacuum clean. I'll have to remind them of this when they're both hospitalised for having a snapped spine, and I'm sat on my bed watching Netflix, perfectly fine.