"Those who live in the past limit their future."
Living in the past can be one of the biggest inhibitors in a person's life to seeing the things that their future will have to offer. In order to achieve the brightest future possible we must resist trying to light up the darkness that is our past. Don't let your past mistakes, and past regrets stop you from becoming the person that you want to become.
Instead let your past be the building blocks of which you build the castle that is your future. In order to see the doors that are opening up before us, we must be willing to take our focus from the doors that have closed behind us. Change is never easy, and we shouldn't expect it to be. We just have to be mindful that instead of fighting hard to hold on to what was, we must instead fight hard to let go.