We're safe in the comfort zone. A person is in their element there, and can usually predict what's going to happen. There are no unpleasant surprises and no serious risks. Outside of the comfort zone is the unknown--which can sometimes be really frightening.
But there are also adventures out there. Thrilling ones well worth having. Often in life, God beckons us out of the comfort zone to take us on journeys like these. To help us grow and to do awesome things. Sure, there might be some unpleasant dips in the road, but as long as God is guiding you, there's going to be a good end.
It could be small or something huge. Reciting a speech in front of a group of people, or going on a mission trip. But whatever it is, as long as the Lord is by your side, things are sure to be great!