I don't remember any big experience that I overcame a challenge. My related experiences are all too small to mention. For example, I didn't learn physics in my high school but we have physics subject in 1st year of my major and physics is important in my major. So I learned physics with online lecture before the midterm exam. By doing that, I could finish my midterm exam well.

Hello, Seong Eun!

Thanks for writing your homework! ^^
See you tomorrow~

-T.Jhozel 

I don't remember any big experience that I overcame a challenge. 

>> Correct!

OR: I don't recall any major experiences in which I overcame a challenge. 

My related experiences are all too small to mention. 

>> Correct!

OR: I have far too few experiences to share that are relevant. 

For example, I didn't learn physics in my high school but we have physics subject in 1st year of my major and physics is important in my major. 

>> Correct!

OR: For example, I did not study physics in high school, but we do have a physics class in the first year of my major, and physics is important in my major. 

So I learned physics with online lecture before the midterm exam. By doing that, I could finish my midterm exam well.

>> Correct!

OR: So I studied physics with an online lecture before the midterm exam. This allowed me to complete my midterm exam successfully.