Lower abdominal muscles - VERY important

"If I'd told you what you had to do today, you wouldn’t have shown up" says Luke, at my first Personal Training (PT) session.

Is he lying? He doesn’t look like he's lying.
A nervous laugh from me, but my swallow sticks in my dry throat, and it's with something of a sinking heart that I realise he's serious.
I have to run (Forrest, run). Full pelt. Up a steep gradient. For as long as I can (hah!).
This is apparently the only way to measure my body's ability to absorb oxygen from my lungs.
Let's cut to the chase, I lasted 2 mins 45 seconds. Luke reckons he's made it to 12 minutes in the past. I'd love to scoff that this ex-services fitness fanatic is full of hot air, but looking at him - I can believe it.
Shame faced, chest burning, heart screaming, some more calculations incredibly, nay, unbelievably show that I once again fall into category 'good' for oxygen consumption. There has to be an easier way.
The rest of the session comprises core stability and strength - my ex-gymnastical days have put me in good stead for this, and the stretches and crunches placate me after The Ordeal.
However, after a depressing discovery that my lower abdominal muscles need some serious work, Luke tells me something which at once changes every single one of my goals. Not just in fitness, but in life, generally.
He once saw a video of an elderly lady who's lower abdominal muscles had all but disappeared, pass her bladder through her… "you know" . His head nods the direction of a place I have no intention of ever seeing my bladder protrude from.
This is now my sole motivation. There is no more important goal.
You will have to check back here in about 40 years to see if its worked, though.