I have heard a person, whose name is Robbie Dawkins, describe a principle in weight-lifting. Failure is the goal. Obviously, as in everything, failure is not really the goal. But success, growth or improvement do not come unless we push to the point of failure. The assumption is: we need to know our limits in order to work beyond them.
To be available means we risk failure. Failure delineates our limits. Failure highlights areas we need to grow in. Failure may not be God closing a door. Failure may be God saying "Here is an area I need to teach you about. Here is an area I need you to engage in, to grow in, because I want to grow my Kingdom in this area through you."
To be available, we need to alter our view of failure.