Do not regret what you have done

Miyamoto Musashi understood that dwelling on regret was a luxury he couldn't afford, 

In the face of constant life-or-death challenges, he had to focus on the present moment and the actions that would keep him alive. That's why he emphasized the need for a clear mind to make effective decisions. Because regret doesn't just cloud your judgment, it also chips away at your belief in yourself. Many of us struggle to distinguish between guilt and regret. Guilt can be a helpful emotion. However, regret is a negative mental state that doesn't serve us well.