We can't completely tell but we can feel on ourselves if what we see is already a bull run or not, I mean we have our own judgement and we know when it has already come or not based on our experience in the past. Most probably our basis is only the trend, and if we don't see it, we might not be able to believe but this market is really unpredictable but we should not mind the significant up and down and just hold until FOMO will happen again.
FOMO, IMO is one of the big reason of the bull run, and that time price could be overvalued so its our chance to sell our holdings especially for altcoins that is very cheap and undervalued at the moment.
As for this, we do have our own versions of interpreting the market movement. Those early birds from this market who able to bought bitcoin lower than $1K still considering that the current situations define as bull, while for those who bought from the peak of $20k surely wouldn't agree. Same with your
opinion, it's the holders personal appreciation of market movements. Together with FOMO, it leads the way to spark the bull to try reaching ATH.
You can use past movements for your reference in defining the market conditions.