All problems, big and small, started with someone uttering three simple words "it doesn't matter". It may not matter to you at that particular moment, but it will matter to someone eventually. Granted, you cannot be responsible for all outcomes, but you should always take responsibility for your actions.
Some mistakes cannot be corrected. There are some things that are lost and can never be retrieved. These moments will fill you with regret. For the others, acknowledge your error, apologize to those affected, and move on. Dwelling on mistakes is not a good thing, whatever the motive. The bigger the mistake you overcome, the more others will respect you for it.
I remember when I dropped you. You were only three months old and I put you in your car seat without latching it. I'll never forget that awful sound of you hitting the pavement. Thank goodness it was followed by the loudest cry a few seconds later. I rushed you into the nursing station and spent the next few hours doing my best to console you - while internally beating myself up over my stupidity. I may not have uttered the three words, but I obviously thought them at some point.
I want you to remember not to hide your mistakes. Embrace them, learn from them and - when appropriate - laugh at them. They are inevitable and, as long as you are sincere about making amends, people will usually forgive you. Keep focused on your goal, and embrace the truth - even if it hurts.