This is a good topic, I many times have experienced the same situation where I sometimes get bored of a coin am holding due to maybe no upward movement for sometime, and maybe the coin was going up before I bought, and a few minutes or hours after I bought, it starts to go down and down and down, I get scared that if I continue to hold, I might loose all my money so I will panic sell and few minutes or hours after I've foolishly sold at the great loss, the same coin starts to go up and up and up, in situations like this, I sometimes feel like crying cus I don't understand why I am so unlucky, but then, I would think within me that if maybe I waited, I would have had the luck.
So personally, this experiences have taught me alot of lessons and I've promised myself to always be patient with whatever coin I invested for long term no matter how bad the market performed after I've invested cus sometimes, it's a trick from the devil to make us loose our money because he wants us to remain poor.