Losses are a simple cost of doing business. Don’t try to justify a bad trade by convincing yourself that it will sooner or later turn into a good trade. Accept losses easily!  Successful traders are able to ride through downturn periods. The confidence in their methods reassures them about their future success. 
The markets offer endless and plentiful possibilities. Missed opportunities  exist only in your mind. Prices keep changing and generate other opportunities. The goal of trading is make a net profit after a sequence of trades. It is, therefore, necessary to accept some losses and to look forward without punishing oneself.