Leaving my recent position

I recently joined an NGO for teaching kids who might not be at their best financial stability or even especially-abled. I took 4 sessions there and now I resigned. 

I am not doing my best as a teacher, to be honest. 
This resignation is not for me and might not be for the company but for those kids. 
Those NGOs must be thinking that a teacher is coming from there must be best, I am not the best.

Out of 4 sessions I took, one was bad because I wasn't able to speak I had a severe sore throat, and I don't know if they understood my voice clearly. Second I was sitting in my college garden, there are so many distractions when you sit in the garden, a teacher shouldn't be distracted that much.

My expectations as a teacher aren't fulfilled, I am not a good teacher. 
The people there are so good, they are so nice, there can't be a better workplace than that. 

Maybe not this year but later maybe in 2025 or even 2026, I'll go back, when I'll be stronger enough to be a teacher.