We tend to think of power in terms of big, burly men doing manly things. You know, lifting barrels, punching people in the jaws, carrying wives, and growing mustache. This ideal of power extends to other aspects of our society such as the military where big, bad weapons are the name of the game. But Asimov thinks of power differently. In Foundation, power is subtle. For Asimov, true power comes from a rational man's ability to control technology, politics, or even other people through his ability to think his way through a situation. Team up power with forethought and control, and it'll take on the burliest, manly man you've got and come out on top. The exception being arm-wrestling Sylvester Stallone, of course.
The only protagonist who actively seeks power is Salvor Hardin.
Hardin is also the only person in the novel to seek power and actually obtain it. All others who seek it are destroyed on their quest.