What can I do to have my destination confirmed?

I have seen a lot of great buddhists who change their paths due to some kind of conditions. Recently, I also face a that kind of situation. When, I faced a dissapointment, I forgot all teachings that I have learnd. It got some time to understand the situation. It just a small one and I had knowledge to understand the situation. There may be some situations that out of my understandings. What can I do to have my destination enlightenment , confirmed ? Related question: What makes a monk to be a house holder ?