Focus becomes easier when the objective becomes specific.

Vague objectives make focus almost impossible, because there is no clear next action and your mind keeps drifting toward things that are better defined. Specificity gives attention somewhere to land. Much of what feels like poor discipline is actually poor definition.

When you cannot concentrate, check whether you know exactly what you are trying to do right now. If not, spend five minutes making the target concrete before trying again. Clarity often solves what more willpower would not.