In my experience, everyone will say they want to discover the truth, right up until they realize that the truth will rob them of their deepest held ideas, beliefs, hopes, and dreams. The freedom of enlightenment means much more than the experience of love and peace. It means discovering a truth that will turn your view of self and life upside down. For one who is truly ready, this will be unimaginably liberating. But for one who is still clinging in any way, this will be extremely challenging indeed.
How does one know they're ready? One is ready when they are willing to be absolutely consumed, when they are willing to be fuel for a fire without end.