I don't know what your financial situation is, but if you wanted your money to work for you, you could make a relatively safe investment that would provide you with that income. You could stagger dividend paying stocks or bonds so that you could receive payments each month, or you could buy enough real estate to achieve your goal.
These are the most ideal options, however, if you have no money to make the investment, I suppose you will have to resort to trading your time for money. I think what you are looking for is a reasonable amount to make writing online, but it will take time to build that sort of readership. You could maybe start a part-time business too, depending on how much time you have. Hope that helps :)