Conviction

I'm a believer that high conviction in a small number of areas is crucial to accomplishing goals and is correlated to personal happiness.

Conviction is defined as:

a firmly held belief or opinion.

I think where people often get the concept wrong is believing that off the bat, in order to have high conviction, one has to achieve 100% certainty.  It's important to have high conviction when one arrives at 80 - 90% certainty while leaving room for error.  The benefit to having conviction earlier is 1) leads to action and 2) it's nearly impossible to get to 100% without testing.

Action allows the testing of the original hypothesis which would then either validate or deny the original assumptions.  The findings would uncover new information which pushes closer to 100% certainty.

Humans are naturally uncomfortable with uncertainty as it represents potential for downside but where I believe we often get it wrong is the downside isn't as impactful as we'd think.  Humans are highly adaptive and it's often surprising what we can handle.