Positive thinking

Yes positive thinking...
A person is needed to have positive thoughts. If you don't have positive thoughts than you need to do work on your positive thoughts. ?

Reaction on thinking

Reaction? Yes of course reaction.
Do u know there is reaction in every thought...!!!
Even not only reaction but also reviews are present for reaction.

Thinking is necessary?

Yes, of course it is necessary.
There are mainly two types of thinking.
1st-Positive Thinking
2nd-Negative Thinking.
Among these two positive thinking is necessary in person's life