Yes, I haven't mentioned that in the post, but that's definitely a good point. Our happiness or satisfaction will be very much linked to progress we make. And

Yes, I haven't mentioned that in the post, but that's definitely a good point. Our happiness or satisfaction will be very much linked to progress we make. And since progress tend to be logarithmic (the last 20% taking 80% of the time), the last bit will be the least pleasant. So that's where we become less efficient. Of course that doesn't mean either that we should stop when it gets hard. But being aware of this should help you decide if you should keep pushing or if it's time to take a break (which can be a few minutes or maybe weeks).