How to help a person mired in a fantasy world ?

I have a friend, not bad in general, man, good, but too carried away by his imagination and fantasies, he lives them.Constantly telling fantastic stories about the alleged his exploits, and is convinced that all this believe.It looks very absurd, however associates perceive it as a dupe and do not want to do with him.He too realized in life, and I really want to have it finally all came together, but it is necessary for him to live a reality and no longer persecute the their bikes.How can I help him?How to talk to him about it, so as not to hurt and made conclusions?