A longing is a sign that your body, mind, or soul wants some thing.
Which on the body level could bee as simple a a bar of chocolate.
On the mind level it could be the need to make amends...Or the desire for a new challenge.
The quietest and most persistent longing will always be that of the soul.
And is the one that will have the the biggest answer..
Sadly...How ever i can not answer this question for you.
Your Body, Mind, or Soul already know the answer....Which is not out here.
But within yourself.....So the only answer i can give is this.
Will you listen to that small voice within yourself..........Or take other peoples word on what you need?
It means that you are not acting / interacting.. and just waiting for something to come and occupy you.. which does not work.. instead trying getting into life of as many and start keeping track of them... and soon you will find yourself bizee and no time to sit n long...
but be yourself and just don't be someone's beLONGING, too early.
Angst... or what daredevil221 said.
Not used creative or sexual energy.