Discipline in trading is especially hard for forex traders

OANDA:EURGBP   Euro / British Pound
I love trading forex due to many reason one being the high volatility . You almost always get second chances for entries and exits. Prices tends to oscillate around their "fair value" al to more than in Stocks or ETF´s. There is almost no pair the rallies 50% in a year.
While there are scenarios for early exit, one should only execute such planed exceptions right? But even after 12 years of trading my n°1 mistake remain early profit taking!