The passing of time does interesting things. It tends to put a golden light upon the lovely times & somehow seems to dull the darker ones. But still, certain things bring out those forgotten emotions pretty strong. Memories come flooding back to you & your past experience really doesn't seem past at all. You wish you were there again at that beautiful place looking at those awe inspiring buildings and art. Or feeling the strong acceptance & happiness you've felt with friends & family. Or re-living those days filled with stressful excitement & anxiety but ended up so absolutely great. But then something somehow reminds you that things are different & to enjoy the stage of life where you are. So that later on you can look back with the same fondness about the things you're currently experiencing.
Like you, I've had some really wonderful memories about my times wandering through love, adventure, college, friendships, family relationships, religion, continents, & cultures. Most things I like to remember. Other memories cause a little too much longing. While others have a very special place in my heart. Memories are a way of holding onto things you never want to lose & I guess that's what life is all about, is it not? Experiencing life & allowing the memories to make us a better person for it.