How Persistent Are You In Prayer?

How many times must you pray the same prayer and ask God to do the same thing before He hears you?  Once, twice, or day after day until you get what you are asking for?   Tough question, right?  There are times when something bothers you and you pray about it.  Nothing seems to happen so you pray again, and again.  Or, may you give up entirely, thinking you don't know the right words; or you think, "This may work for others but not for me!"