Example 1:
Pete:  I’m usually the wallflower of the party.  I’m not very good at socializing.

Chip: Dude, you really have to stop doing that. 

Pete: It’s not so easy man. 
You can say that because you’re always the life of the party. 
You’re always talking to everyone, introducing others, and making sure
everyone is having a good time. 

Chip:  You think I’m the
life of the party?  Wow, thanks
man.  I never thought about myself that
way.

Example 2:

Kazuyuki:  Being the life of the party comes naturally to
many people.

Ting:  Are you kidding me?  I think it’s something that you have to work
on.  You can be social, but that doesn’t
make you the life of the party.  To be the
life of the party, one should know most of the people in an event, be aware
of everything that’s going on, be a good host, and entertain everyone.  That takes serious communication and
organizational skills.

Kazuyuki:  Or you could just
be very good looking and charming.

Ting:  You’re so
pessimistic.  You’re definitely not the life of my parties.

Meaning: The life of the party is used to
describe someone who keeps a positive environment for everyone and is always
making people feel good.  People who are the life of the party are: usually
social, outgoing, organized, and have a good sense of humor.  Being the
life of the party requires good social skills and a positive attitude.

www.languagesystems.edu