[Poc]

For things like textbooks, I'll start easily but then, when I reach a new point or new chapter, I will rationalized my self to stop it there and call it a done work, when in reality I worked only 30 minutes instead of and hour.

it's like my mind is rationalizing itself to settle for a sub goal.

[Apocryphon]

That's where the Pomodoro technique might be useful. If one adheres to it, it does what the article describes as "making the decision in advance." After you take a break after the stopping point, the technique makes you continue on. But of course, that means you have to embrace the plan and not resist against it, either.