A question for securities or derivatives brokers...?

I was considering a job at a derivatives trading firm. This job would be 100% commision based. I know that once you have a large base of clients the job can be very lucrative, but how difficult is it to achieve a livable amount of income?? I am asking because I would like to get a good idea of how difficult it is from the sales aspect so that I know what I'm getting into, and dont end up starving or living out of my car!