It's a very subtle feeling. It is quite hard to recognize straightaway. Not until it's too late sometimes.
It can sometimes mask itself as 'being cautious' or 'being careful'.
It can block you from achieving your dreams through a very powerful mind game called 'what if'.
In many cases the difference between success and failure is just a few split seconds that we take to hesitate. Then this hesitation takes hold, giving us a false sense of security, lulling us into a state of inaction.
But guess what, people have figured out that to achieve things we need to push through some barriers and overcome our fears: 'No pain, no gain'. So, what else is there to say, apart from: 'Just do it'.
And it doesn't matter if you get it right or wrong. Just do it.