Every moment we breath out we die and every moment we breath in we live. With death we lose past and then with every new breath we compose life. Your future life is composition of these events or karma and you simply add them on to get richer life experience.
Therefore it is futile to hold on to dead past and crave for more in the dead future because what you have is this live miniscule moment. Use it to construct or destroy. Anyways destruction is automatic with each passing breath and you can double it up in the life breath too.
So the positives like love, compassion, forgiveness, goodwill, innocence and hope can be nurtured as against anger, frustration, hopelessness and hatred.