I reached a conclusion the other day
when I was contemplating
the regret phenomenon :

You don't feel regret for the things you've done,
you feel regret for the things you haven't;
You don't feel regret for the words you've said,
you feel regret for the ones you haven't;
You don't feel regret for the love you've expressed,
you feel regret for the love you haven't;
You don't feel regret for the lips you've kissed,  
you feel regret for the ones you haven't;
You don't feel regret for the hands you've held,  
you feel regret for the hands you haven't;
You don't feel regret for the smiles you've thrown,  
you feel regret for the ones you haven't;
You don't feel regret for the things you've done,  
you feel regret for the things you haven't;