^I agree 100% with this.
An article I read a while ago explained how we tend to be more afraid of threats that we are less...familiar with as opposed to everday threads. For example, getting in your car and driving to work. Look at how many people get injured or die in care-related accidents every day. But (most of us) depend on a car to get to work, get around, we are used to them, also used to hearing about accidents - but still we don't worry constantly about getting hurt on our way to work.
It's just highly unlikely that you are going to die in a terrorist attack - so just do what you would normally do and enjoy life = you win.

Plus, the world has always been a very dangerous place, there have always been terrorist attacks, long before IS: we had the RAF in Germany, the UK had the IRA - to name but a few. These days, we get much more information way quicker than only a couple of years before so it's easy to come to believe things have gotten a lot worse - but I honestly believe that is not the case.
I'm going to a show tomorrow night - Black Star Riders - and while the poor people at the Bataclan will certainly be on everyone's mind, I am certainly not afraid.