Never regret your past. Rather, embrace it as the teacher that it is. -Robin S. Sharma
Don't forget all that you have ever learned. Every memory that you have is a part of you. Every fight, every love, every relationship, every dinner, every graduation, and even every school day have left some kind of impression upon you, and have made you exactly who you are presently. Don't try to disregard the person you used to be by just trying to sweep that person under the rug! Embrace your past, even if it doesn't make you happy when thinking about it, it can make your present much more pleasant, and your future days much brighter.