You were always a bullied and weak person in your school so this is when your parents enrolled you for martial arts, specifically taekwondo, you were still shy about going in so your coach had to drag you in the gym

"Whats your name..."

He says this in a cold expressionless tone

"You look thin..." He mutters

"I bet your new, well looks like I have another student to train. Lets start training"

The brown belt kids were teasing you, you tried but failed to do a split