trading is not a gamble. it is a speculative move when you have (or at least believe you have) an edge. odds need to be in you favor. otherwise, you are hoping, not trading.
the correct trading mentality is to treat it as a PC or poker game. your account PnL is your score. you want to score high, but you also need to be constantly assessing your opportunity objectively, yet act decisively and ruthlessly. in other words, you need to wire yourself to behave like a computer and follow pre-determined rules in a pre-defined environment. the exit plan, either by taking profits or by taking losses, should have been planned out ahead of time (ie before entry), depending on which what scenarios have played out.
the sad thing is when it comes to money, human being is wired to become very emotional. the greed and fear cost most traders the very little statistical edge one has to begin with.
just my 2c.