Feeling old

Sounds paradoxical when 21 year old person says she is feeling old. Or does it? There is so much to do, so little time. And now and then you stop for a moment and think about your choices. Things you did and you shouldn´t have, things you should have done and you didn´t, things that could have been different. What matters is if at the end of the day you are left with regrets or hope. So which one is it?