It's not about what you won or lost in your last trade.
It's about knowing that your methods have been reliably proven to have a collective edge (positive net expectation) over a statistically significant number of trades identical in circumstance to the trades you're taking.
Individual outcomes don't matter, when you know that.
One way to feel confident about that (which helps many people to deal with the negative emotions associated with "immediately recent losses") is to develop a good understanding of the underlying statistics and probabilities with which all traders need familiarity.
I think books like Michael Harris's Profitability and Systematic Trading (Wiley, 2007) are a great confidence-booster (for people who take it to heart and incorporate its teaching in their trading) and a help with negative emotions.