If you didn't have doubts

Think about it.

You would walk blissfully unaware.

Do i have doubts?

Constantly.

The only thing I was sure about was math,

  and I worried about some of the physics.

Now, 

 back to doubt,

 or at least doubting yourself,

  there is nothing wrong with it.

It means you are paying attention to the decisions you are making.

None of us are perfect.

  Why not look into our decisions?

By the way,

  the us should have been you.

I have  an egotistical standard.

Yet, I still made a mistake...