When you enter/take any trade, you should know your stop loss, targets and duration to carry on with the trade. The direction of the price wont affect your capital if you have a proper plan about the trade. It will save your capital and will make you profitable in long run.
No one knows how long a trend will have strength, how many days/weeks the same trend will remain. But everybody knows price will retrace or reverse. So when the trade you took works well & if it is moving beyond your targets, book partial profit and trail the profit for the remaining position. This will help you to get maximum profit from the market. When the trade you took is not moving as per your expectation & reversing means, book loss at the decided stop loss. Dont hesitate at that time. It will generate huge loss if the price has reversed.