Fitts's Law states that the amount of time taken to move to and select a target is a function of the distance to and size of the target.
If you want to make an action more easily selectable, make it larger and position it nearer to the user.
Fitts's Law has direct applications in User Interface Design.
Although Fitts's Law was relevant to the physical world, it still applied to digital design.
Call to actions
If you would like to make a CTA easily selectable, make sure you make it large enough.
Also give consideration to where the users point of interaction will likely be (i.e. where will there mouse be when they enter the page, or what is easily reachable if the user is on a mobile.)
It goes both ways
Fitts's Law can also be used to purposefully make something harder to select. Actions such a "Delete" are often made harder to select by making them smaller, in order to recude the number of accidental clicks.