It’s best to focus on today, here-and-now, because that’s where you have control. Make reference to the past so as to look at what did and didn’t work, and why. The purpose of doing so isn’t insight for insight’s sake, but to solve the current problems. Life isn’t just about solving problems, either. It’s also about making things better. Sometimes outlook is the problem and we’re not even aware of it. Course corrections in attitude can solve problems we didn’t know we had. This is particularly true with things such as anxiety and depression. Dwelling on the past and indulging in regrets are about the worst things you can do to yourself emotionally. When you notice either of these happening, distract yourself and change course as quickly as possible. Make a list of ways to do this and grab that list when you find yourself in the realm of regrets. In the end, the only way to address regrets is to tell yourself, “I can’t change the past. I can only act in the present and influence the future. The past, if nothing else, can give me insight. That insight makes me more powerful in the present.”