I can't even recall the last time I set a target for gambling – I mean funding my balance with X amount and expecting to make XY amount before the end of a given period. That makes gambling more fun to some point, but it also puts a lot of pressure on me to be much more calculative. Even when, in the end, I, as the player, can't guarantee the outcome of all my games, I still will put that pressure on myself, which makes it more fun and, at the same time, painful when you lose such a bet.
This is gambling, so no one can really assure that you will win on your every bet. So for you not to have any problem, make sure you are only playing using your extra funds. It may be so popular mantra among gamblers, and yet, many are still falling from the temptation of this activity.
I can understand that many gamblers here are aiming for one big winning at one point, but should accept the reality that it is not for all. Do take note that once you hit some winnings, most of the time, you will go back again aiming for more. So that's actually greed, which is human nature.