If you're in love with somebody, but that person doesn't know...
tell her/him. Maybe today, that person is also in love with you. And if you don't say it, tomorrow can be too late.
If you still love a person that you think has forgotten you...
tell her/him. Maybe that person has always loved you. And if you don't tell her/him today, tomorrow can be too late.
If you need a hug of a friend... ask her/him for it.
Maybe they need it more than you do. And if you don't ask for it today, tomorrow can be too late.
If you have friends whom you really appreciate... tell them. Maybe they appreciate you as well. they may leave or go far away today, tomorrow can be too late.
If you love your parents, and never had the chance to show them... do it. Maybe today you have them to show them how you feel. if you don't and they leave today, then tomorrow can be too late.