SI is millions of years of biological evolution at work. The body and brain want to live at all costs, it is our purpose in nature. It's not just about courage, you have to overcome something larger than life. I have no advice, it's something you have to understand and conquer on your own. Most people are scared in the end, it's a human trait. If this is truly what you want then seek ways that will keep you calm. If you have any doubts, any reasons to stay, it's okay to see what life has to offer instead.