The default state for humans is action, not inaction. You can see it easily in toddlers who must be doing something at all times. If you ask them to stop, they can’t. If you ask them to do something else instead, they can. They can’t stop hitting their baby sister, but they’ll switch agreeably to hitting a ball or stacking blocks instead.
With adults, it’s more obvious with mental activity and social interaction. If you’ve tried meditation, you’ll know how hard it is to empty your mind. Even when you manage it, and you’re contemplating nothing, there’s still that awareness of contemplation and of nothing. The activity is still continuing. Maybe you’ve also experienced the discomfort of an empty, quiet room and the itch to go online or text someone or turn on the TV. Action is our default.
This matters when theories of human action assume that it occurs against a background of inaction. The assumption is that you are in your default state of doing nothing when you respond to a stimulus of some kind or are motivated in some way, and those external inputs cause you to act. If we assume that action is the default, in contrast, then the stimuli and the motivation are unnecessary, because you would act anyway with whatever’s available, just as a toddler will pick up leaves and bits of rubbish to play with if he happens to be out on the footpath.
The action of influencing you from one action to another is very different from motivating you to act from scratch. The first only requires that one option is more salient or attractive than the other competing options, and the bar might be very low. If we assume that inaction is the default, then to stir someone to act would require them to pay the cost of expending energy. The chosen action must be justifiable in some way. If action is the default, then each individual action does not need to be justified, but only understood in terms of the context, in the same way that we might try to understand the particular path a river takes.