Yes, investing always involves a realistic attitude and it is very important to have a clear plan of when to buy and sell your investment. This is especially relevant when compared to emotional decision making based on short term market fluctuations which can lead to bad investment decisions and losses.

Although having a set of pre-defined criteria for buying and selling, such as a certain price point or changing market trends I also think this can help remove emotion from the decision-making process and increase the chances of making a profitable investment.