Is there such a thing as "no regrets?"

I heard someone say recently that they live their life with no regrets because everything that has happened to them has made them who they are. I really have thought and prayed on the subject because I do feel like I regret some choices in my life. Regret, as a verb, means "to think of with a sense of loss" or "to feel sorrow or remorse for." Regret, as a noun, means " a sense of loss, disappointment, or dissatisfaction" or "a feeling of sorrow or remorse for a fault, act, loss, disappointment, etc" (both are from dictionary.com). The fact is that I do feel like I have things in my life that I feel sorrow and remorse for. I have feelings of remorse for a fault, act, loss, disappointment, etc. Let me clarify, though....
The phrase "Everything happens for a reason" could not be more true, in my own mind. I do think that things happen for a reason and that there are seasons in people's lives. I do think that "sometimes bad things happen to good people." Don't get me wrong. I am not blind to the fact that the experiences in my life taught me lessons and that some of these experiences changed my habits. That being said, I don't think that the experiences changed the core of my being.
I am a firm believer that there are a number of factors in your life that shape who you are from the date you were born to your birth order to your name and obviously environmental factors such as family life, friends, etc. I think that the essential core of your being remains the same no matter what. Christ being in your life gives you a relationship with him and gives you a passion to be more like Him but essentially you still have to battle your bad habits one at a time (though with God's hand, it's much easier). I don't think there is much that affects your essential makeup because God created you a certain way and He doesn't make mistakes. I believe that some people are more shy than others by nature. You can change their habits but you can't change their essential make up. I believe that some people are outspoken. They can learn to shape their habits, but their desire to be outspoken will never change. I honestly don't believe that people's essential makeups change....only their habits.
So, getting back to my original question, I don't think that the experiences in my life made me who I am. I think they changed my habits...they made me appreciate certain things more, they made me more frugal, they made me more conscious of certain things, and so on and so forth. Big events let me know who my "real friends" were and how I should expect people to react in a crisis. Ultimately, though, it gave me knowledge and changed my habits, but not me. I don't believe that people have reset buttons. I don't believe that you can just flip a switch and make them something that they're not. They still have the same desires and passions...they just learn what to do with them (good or bad).
There are people that I regret hurting in my life, through words or actions. There are people that I regret felt hurt by situations that I watched. There are people that I have let corrupt my life for longer than they should have. There are people that I should have fought harder to keep in my life and there are people that I should have told to go pack sand. The fact is that I regret the way that I treated some people (good or bad) and how I let people treat me sometimes. The fact is that I regret some of my decisions and that I would change them if I could. The fact is that I do experience sorrow over some of the choices that I've made. I don't believe that there are honestly people that have no regrets. I believe that it is something that people tell themselves to make their minds feel at ease. Regrets are okay if you learn from them and God is a God of second chances. You may have a chance to remedy those regrets.