Thank goodness I changed that attitude or I wouldn't be where I am now. You have to let people and opportunities in to be able to experience certain things. You have to knock down your walls to see what's right in front of you that you may be blocking. It's OK to let go of your safety net sometimes -- in fact, it can be far more than OK if you are willing to let it be.
Is there a person or opportunity trying to present itself in your life right now? Are you afraid of what will happen if you take the next step? Yes, you might get hurt. But what if it would have been the best thing that ever happened to you and you didn't let it in when you should have?
If you have general good feelings toward something, don't let it go.