I agree with Michael. I haven't heard exactly this expression before either. But it sounds similar to the expression 'to take your foot off the gas', meaning to ease back, to reduce your efforts to achieve something, to slow down, to relax... This metaphor comes from driving a car: when you you lift your foot off the accelerator, less gas (gasoline: US/ petrol: UK) goes into the motor, and so the car slows down...

I agree with the other answers about the meaning. It’s a common idiom here meaning ‘slow down’ or ‘not try as hard’

Unusual metaphor for me but probably, he means he will not stop pushing hard, he will not slow down or reduce his current rate of effort.