This is off the topic somewhat, but I've been reading about the teachings of Bankei, a Buddhist teacher in 17th century Japan. His teaching is very simple. Originally, we come into this world without thoughts, such as regret for the past, or anxiety for the future. Having thoughts and dwelling on them is something we learn to do, and many of us do it very well. If we can 'unlearn' the process of holding onto thoughts and developing them, life becomes more rewarding, natural and pleasant. That's how I understand it anyway.