Euphoria is a variety of greed which arises after a trader has experienced a streak of winning trades or a single large winner. It builds an exceedingly positive sentiment and confidence often luring you to enter and hold many new positions, usually in the same direction as the previous winner which can end badly.
I think the first thing a trader should do when emotions build up is to walk away from the trading terminal and wait for it to pass.
I think the idea of this is actually silly. You are doing well, enjoy it. You can blame the euphoria for your bad decisions after but maybe it was just the time It would of not worked out even if you are not on a euphoria high.
Enjoy your wins, but if you are experiencing euphoria highs that you feel are messing you up then you simply just do not have your method together enough.
Make sure your method has all If-thens built into it.