My most-used macros are on the Quick Access Toolbar so they can be run with one click. But the Quick Access Toolbar can only accommodate a certain number of macros and after that you have to scroll to find the one you want. Another way of running macro is to assign a keyboard shortcut: in the same way that Ctrl+C will copy the selection, Ctrl+SS for me will lower all the subscripts by 2 points and raise all the superscripts by 2 points as described here. All single letters are already used as shortcuts so, instead of reassigning them, I use two letters.
To assign the keyboard shortcut Ctrl+MB to the macro to replace the Cambria Math font in equations with Arial font as described here, follow these steps:
Select File>Options>Customise Ribbon to bring up this:
Under Choose commands from select Macros then at the bottom of the page find Keyboard shortcuts and click Customise:
Under Specify a command in the left-hand table select Macros and in the right-hand table select the macro to which you want to assign a keyboard shortcut. Under Press new shortcut key enter the shortcut you want:
Then press assign and close. The macro then runs when Ctrl+MB is pressed.