"But I already put so much work into it, I just have to make it work."

"I spent a whole year studying graphic design, there is no way I can quit."

"I hustled so hard for the past few months, I can't give up everything I built."


I'm right there with you.
You are stuck in the trap of SUNK COST BIAS.

Should the teacher get a job as a lawn mower?

You guessed it!
My answer to every question is - it depends.

During the school year he could instead be making more money working as a teacher.
During the summer time, he would not be teaching anyway. Therefore any money he makes mowing would be extra.

Every choice you make in life and business has an OPPORTUNITY COST.

"Huh, Huh, Huh!" the student waves her hand eagerly, wishing to be called upon.
"What's that noise? Do you have a stomachache?" the teacher admonishes sarcastically. 
The student falls silent, and something inside her wilts that day.

Does this sound familiar?
I've experienced this story many times throughout my school years.