Complex sentence: The willpower paradox is the idea that people may do things better by focusing less directly on doing them, implying that the direct exertion of willpower may not always be the most powerful way to accomplish a goal.
Split into simpler sentences: The willpower paradox is the idea that people may do things better by focusing less directly on doing them. That is: the direct exertion of may not always be the most powerful way to accomplish a goal.