You cannot cross over your comfort zone. You can stay within it, or you can leave it or get out of it.
Your question needs clarification. Did you leave out an initial What?
It's a bad sentence, but I guess the idea is that you have to move outside your comfort zone to really live- if you stay inside it, you will restrict your experiences.
I don't find it a bad sentence. I agree with Tdol's guess though - if you stay within your comfort zone, you're not really living. If you have the nerve/bravery/courage to move out of your comfort zone, you can really begin to live.
It's similar to "Life begins at forty" although of course everyone hits forty years of age whether they like it or not. Moving out of your comfort zone is a choice.
Many happy returns :new-bday: (it's already tomorrow here)