Dear fast food workers,
You need to understand, you cannot make $15 an hour.  I know you want to, everyone does, but it is simply not feasible, at least not as a fast food worker.  Recognize that if your salary jumps as such the prices in your store will jump, and those of us NOT granted a 100% pay increase would stop coming to your store completely, meaning you would have a 100% pay cut (you'd lose your job).  If we press the minimum wage up it drives up other prices, basically putting you back at square one and dragging others that were doing a little better down (because they don't get a boost in pay to compensate for the increase in prices).
 
Heck that might happen anyhow.  I know if I owned one of your stores and had 10 employees at $7.25 an hour and I was forced to increase that to $15 an hour, you best believe I'll be doing my best to see what I can shift around to get by with only 5 or 6 to minimize that loss of revenue on paying my employees.  What can I do to automate or make more efficient?  What jobs can I double up?  Who can be pressed to add one more task to their to do list and alleviate it from someone else.  You can also trust that you will find a great deal more competition for the position you hold, and you best be concerned if you don't consider yourself good at math or fast in completing the tasks at hand.
 
You can however choose to work towards a skilled labor position that does in fact make the kind of money you're requesting.  Understand that your current position is one that many people consider to be positions for high school students, short term work, part time jobs, a starting point, not a career.  If you truly love the work that is fantastic, but I hope that there are opportunities for you to advance there such that you can assume a management role making and justifying the wages in question.
 
If I don't like my job or the salary they give me I can ask for more (not mandate that you pay me more even if I'm not qualified) or I can look for another job.  I'm pretty sure someone else would love to have my job at my current salary.  This is the concept of supply and demand.  If I had some awesome knowledge or unique skill set the chances of them replacing me easily are low, so I have a better chance of getting a pay raise to stick around.  Are you confident that no one else would want your job for what you currently make?  Hell, if I lost my current job and your position paid $15 an hour, that might make it onto my short list of temporary positions to keep my bills paid. You're on notice.