There are multiple boot drives on my Mac. If I want to use one other than the default drive I need to hold down the Option key while it's booting up. Then when the available drives are displayed I select the one I want and off I go.
And I've just wasted 45 seconds of my life! I've got other stuff to do that I can't do while I'm stuck an arm's length from the keyboard.
So here's an alternative: The Paper Clip Option Clip
Step 1: The Raw Material:
The raw material:
One large (not the wimpy small type) paper clip.
Step 2: Crafting the Solution
Lift the smaller loop up and back allowing it to bend at the places shown.
Step 3: Freedom!
After your Mac make its initial "bong", slip the paper clip between the Option key and the bottom of the keyboard.
Now you can run around and do whatever florid little tasks your heart desires. I usually check my phone for messages.