This days are test for our emotions, when we see that market is rising we always questioning ourselves to sell, to wait, to buy more, what to do and to take most profit in the end.
Its easy to talk how to control emotions in calm times, in moment when everything is happening its hard to stay with clear had thats why we must build ourselves in practice, there is no other way to learn how to control emotions.
Yes, many of us become nervous and controlling emotions cannot be learned from the books. The books and literature only teaches you how to. The rest of the work is yours depending on the application of what you have learned but I think facing the occasions make you strong enough to control them. Simply is that practice makes a man perfect.