It's just a simple yes or no, whether you think at least one or more of the candidates on your ballot list shares a lot of your concerns, beliefs, et values to at least vote for them

If you don't approve any of them, just don't mark them, and write down "I don't like any of these candidates" as a reason

I don't like "first past the post" for this reason... it just perpetuates the idea of "spoiled" votes...