depending on how much you know and how you feel about something. Try to learn as much about cryptos as possible and trade as objective as possible.
I think what he is just trying to say is if it is good to have full belief in the cryptocurrency one is trading without having feared or doubt about it. I guess there cannot be any general definition on this as trading an asset includes lots of factors which may change over time. When factors are varying over time, not getting panic will not be possible all the time for a common trader.
A trader must have to actually believe in his investment that it will yield a positive result but once you are too overconfident in it make a trader blind to quickly see any calamity they may be trying to befall the trade at that time, one must not fear in ones trade but you must still fear for the market, the marketcap might collapse if there is no much buying going on in the trade and if one does not always have this at the back of ones mind, necessary precaution that one need to put in place will be missing.