This is a must when you play poker. You don't win a tournament in the first hour, you don't make your fame and fortune in one day(unless of course you are rich to begin with) and going full steam ahead all the time will leave you broke.
I once heard a saying that went (and I am paraphrasing a bit I know)
"A fortune in poker can take a lifetime to gain, but only a second to lose"
Well I know one bad play in a cash game can leave you biting the dust. And one very bad hit in a tourney of any sort can leave you down a bunch or even out the door. I know have experienced all of those scenarios myself. More times than I care to admit to.
A person can have all the luck and skills they want. But without patience, they won't be as valueable as they could be in the long run.