I think it's when one overcomes their survival instinct (varies from person to person), dependent on one's individual circumstances, and of course, access to a method that one is confident and comfortable with. Also, with methods there will always be some obstacle and the SI will always hinder one from carrying it out (even with peaceful methods), but once the threshold of pain has exceeded the will to live, then it becomes 'easier' for one to implement or go through with said attempt.