Webster will tell you regret is a negative conscious and emotional reaction to personal past acts and behaviors, often expressed by the term "sorry."
Regret can describe not only the dislike for an action that has been committed, but also, importantly, regret of inaction. Many people find themselves wishing that they had done something in a past situation.
I have many regrets in my life.
I regret not doing a lot of things I should have done when I had the opportunity. I regret some of the choices I have made in my life.
I regret my inability to convince others to learn from my mistakes and listen to my advice.
Regret is often a feeling of sadness, shame, embarrassment, depression, annoyance, or guilt.
Regret is also about living in a place that none of us belong -- the past.
So live everyday to the fullest, so you have no regrets.