For (roughly) 99.9% of the population, the level of success you’re able to achieve is directly related to the consistency and quality of your actions. Much like how people tend to be out of shape or overweight because they are not putting in consistent high quality efforts towards eating healthy and exercising, people who are "poor" are generally not putting in consistent high quality efforts to improve their standard of living; and in most cases they’re doing (or have done) several things which ensure that they will not improve their standard of living.
Now, the general path to success is to decide upon a goal, make a plan that achieves that goal and to make all your decisions based on how they fit into that plan. If your goal is to become a doctor, and your current step on that plan is to save up money and to take night courses in community college the question of whether you should buy a HDTV on your credit card is easy to answer.
