Ask HN: What helped you leave your day job and start on your own?

Question to entrepreneurs who left a day job to start their own company, what helped you make the decision? Did you already have a running business before leaving or just had an idea or left your job and started searching for something to work on? I have a few things in which I want to do, but leaving the comfort of monthly salary seems very difficult specially because job enables me to financially help my family. Does that mean I am not motivated enough and it would be idiotic to leave the job? My job doesn't motivate me to do anything challenging and is full of enterprise politics.