One should exclude FOMO and FUD from his emotions forever. There are totally useless and even harmful.
One should stop feeling regret or even some kind of pain when looking backwards on the past charts of BTC or altcoins and think in that way: "damn, I should sell here, before the fall and rebuy here, just here, in this price pit"...
You should act strictly and be cold minded. And never regret anything, just remember that it's very easy to judge now when you know much more about the results. This thoughts are stupid and ridiculous!)