Buddhism teaches that the present and the future are what are important, not the past.

For Today and Tomorrow

Daily Encouragement by Daisaku Ikeda
Saturday, June 22, 2013:

 

It's foolish to be obsessed with past failures. And it's just as foolish to be self-satisfied with one's small achievements. Buddhism teaches that the present and the future are what are important, not the past. It teaches us a spirit of unceasing challenge to win over the present and advance ever toward the future. Those who neglect this spirit of continual striving steer their lives in a ruinous direction.