I follow how I feel about something so for me it's my emotions that primarily dictate my life. I'm very uncomfortable with living my life any other way. <br />
I can't speak for the entire planet but I would imagine we second guess ourselves because ever since we were very young we were told how to do things. Recall childhood when you were told not to touch this or don't do that. This is the "right" path that is the "wrong". Be a "good" girl or boy or she/he is a "bad" kid. <br />
Everyone will have an opinion on how we live our lives and although you become an adult all of those voices continue to remind us that we cannot make decisions for ourselves. <br />
Just like we learned not to trust ourselves it takes time to learn how to trust our own intuition. It's there for a reason ~ and sometimes it doesn't lead to eternal bliss but I don't believe that is always the point. The point is to do it and you learn to work through whatever that choice brings your way.
I believe that when we do second-guess ourselves, we're following our mind more than our heart. Our heart is our first responder, I think so because people are more emotional than mental. I take that back, some of us are and some of us aren't. <br />
I think we second-guess ourselves because we want to follow the logical choice that society is making because of society's reaction. <br />
I know I follow my heart but most people I associate with follow their minds and because of them, I follow my mind, too.
People tend to second guess them selves because alot of times we strive for perfection to the point that we must think about things over and beyond in order to make sure we have covered all of the basis and have complete accuracy. <br />
Another reason is due to past trial and error