A "series" of losses whilst not optimal, varies on it's need for concern, dependant on the strategy you trade. Trading a high probablility strategy and suffering a "series" of losses can definitely mess with your head. Bottom line is PREPARATION - the strategy you trade should have a win/loss ratio as a matter of record BEFORE you trade it. If the ratio remains within the strategy's parameters after the losses - relax. Ensure you have traded the strategy to the letter of course. If you're NOT trading a strategy or the strategy isn't performing......mmmm - maybe time for a re-think!