For me it took a lot of time. There's no prescribed amount and no clear fix. The memories fade but will never disappear. Concretely speaking, what helped a lot

For me it took a lot of time. There's no prescribed amount and no clear fix. The memories fade but will never disappear. Concretely speaking, what helped a lot was journaling and some therapy along the way. Most importantly though was being more vulnerable with my friends and family. A lot depends on your specific circumstances but for me, I had to forgive myself and at the same time try to really reflect and learn from what happened. I reflect less and less on what happened over time because eventually I moved past it. It took me around two years to move past a chapter lasting about six years. Regarding the energy of your younger self, that's a natural thing to happen with age. What I recommend for that is maximizing the amount of new experiences you have and dwell less on the nostalgia of who you used to be. Good luck!