Some intense moments stay with you, some disappear over time. With some memories that make me happy, I replay the memory’s details over and over so that they won’t fade.
Try something. Really pay attention when something has an impact on your day (or your life) and record five minutes of the experience. Write down as much detail as humanly possible. In a week, try to write the experiencce again without looking at your previous notes. When you’re done, compare the two. How are they different?