Put words on the page every single day (or at least five days a week.) The solution to both writer's block and a career is to write. You can't call yourself a "writer" if you are not writing--it's that simple. The other writers (mostly screenwriters) that I know personally who are successful don't stop at one, or two, or three scripts or books. You have to view your career as a constant, perpetual process. You can't fall in love with any idea, because by the definition of the perpetual process, you will always need to move onto the next one--no matter how good the last one was.