I decided to post a brief keyboard shortcut list for Adobe Illustrator for more efficient work with the pen tool.
MAC OS / Windows
Command / Ctrl = will temporary allow you to access the last selection tool you've used
Command+Space / Ctrl+Space = again a temporary access to the zoom in tool.
Option+Command+Space / Alt+Ctrl+Space = zoom out tool.
Shift / Shift = A really helpful shortcut - constrains proportions, angles, movement. It works for almost all actions in Illustrator
Spacebar = Gives you temporary access to the hand tool.
Note: The benefit of using these keyboard shortcuts is that you don't need to always activate and deactivate your line (path) for similar manipulations.