Your willpower is finite. It is only available for a limited time.
The person you refer to as lazy may not be. What if they were assigned that responsibility after they have exhausted their willpower?
I think Garry Keller gets it right when he says you need two types of willpower to succeed. The willpower to do the right thing without distraction or disturbance. And the strength/willpower to support what you have done or avoid sabotaging it.
Implementing new behaviors will tax your will power – except you start from the point of least resistance, making it easier to take the first step to sustain that behavior.
The energy you put into filtering distractions, resisting (or fighting) temptation, suppressing emotions, restraining aggression, suppressing impulses, navigating an environment ridden in fear, or trying to impress others will take a toll on whatever is left of your will power.
Flow happens when we align our interest with the willpower available. Focus on what matters first when you still have your energies intact. And this is not new advice. Paul Graham has written about maker schedule and manager schedule. Cal Newport has encouraged deep work – carving out time to concentrate on the most important things without any distraction.
If you can, create a natural environment that filters away those things capable of draining your energy, so you can invest it in the things that matter.