One of the keys to success in life is you have to think big... then persistence and a good dose of attitude will do the rest.
Of Course, one should remain grounded in reality and make sure that even the wildest dream has a at least a tiny chance of succeeding. However, thinking beyond the current obstacles, imagining things much larger than they are at the moment is important as well.
As they say, it is better to be an optimist and be wrong than a pessimist and be correct. Assuming the situation is terrible, then by being optimistic, you at least make the ride more enjoyable... if things are messed up, there is no point in making things worse by making yourself miserable and reminding you how bad things are. However, if there is a remote chance that things can get better, by seeing further down the road, seeing how good things can become, you give yourself the energy to persist and find alternative paths to get there.
So go ahead, think big, pick something awesome, persist and make a difference. It's fun to make the impossible possible.