This is how I started working out regularly. "I can quit 5 min after warming up".

Five minutes after warming up I've changed, in the gym and a couple of sets in. I quit maybe 1/20 sessions, and it's shrunk more over the years since, but it was an easy way to fool my brain.

I'm guessing this is different because the main threshold is starting to do the thing. Once you've started it's much less mental effort to keep going and just do the full workout.