Answer:
The more of me there is the less you see.
I start with T end with T and within me is T.
While you were folding a letter you got me. Usually you will do whatever it takes to avoid me but now you can't help but find me.
I am Invisible Man's drink at snack time
I am the key that is the hardest to turn
It's what light turns into in the night
What am I?
Animal
Difficult
Easy
Food
Funny
Kids
Logic