One way to think about life is as a collection of memories. Whether you are 30, 50, or 80, you cannot physically visit the previous portions of your life.

However, there is one way to revisit those memories. Your present life is the product of all your previous decisions and experiences, so simply being aware of this moment puts you in touch with the past—or at least that sliver of space where you and the present meet.

There’s an even more vivid way we can revisit our past: through our memories.

Since we all experience memories on a regular basis, it’s easy to discount them as ordinary. But memories are anything but boring. Somehow, our brain was designed to, at a moment’s notice, pull up a clear picture of long-ago events. With that picture, there is often a host of emotions and feelings that were present at the time, and some are the result of looking back.

There are some memories I have that make me deeply happy and others that remind me of sad times in my life. Some make me proud, and others are embarrassing. I cannot forget some of my memories even if I want to. Others I cling to because I cherish them so much.

Our memories make us who we are. They give us a sense of identity and help us decide what we want in the future. A life without memories would be far less rich. That’s why, just as a good photo book reminds us of great adventures alongside ordinary days from the past, I think everyone should try to keep a mental or written catalog of their most defining memories.

9 Memories Worth Keeping Alive

1. Early Memories With Your Best Friend

I still remember playing backyard baseball with my neighbor on hot summer days that felt like they went on forever. My definition of happiness will always retain some aspect of this core memory, and for that, I’m grateful.

2. The Moment You Fell in Love

The early memories of blossoming love are filled with some of the strongest emotions known to humans: desire, infatuation, pleasure, and a potential mix of embarrassment and worry. Keep these close and remember that this is what it means to be alive.

3. The Happiest Memory of Childhood

Think about your childhood home and the activities that used to take place there. Even ordinary moments such as eating dinner around a table or doing your chores fill you with nostalgia. One of my favorite memories is of Friday nights with the whole family, during which we’d make a special dinner together and watch our favorite shows.

4. A Setback or Failure

I mostly like to dwell on happy memories, but it’s good to reserve some space for the hard stuff, too. Those hard things, such as big failures, are part of who you are and shaped you in more ways than you can possibly know. They may be a clue to some future discovery about yourself.

5. A Time You Fell Short on Your Values

We’re going deeper into the pain with this one. Letting yourself down is hard, especially when it’s a core value. This can be a direct blow to your identity and cause you to question important aspects of life. Hold these moments close so that they don’t get lost. What’s in the light can be overcome.

6. Reading a Particular Book

I’ve written about the books that shaped my worldview. Part of the reason I wrote those down was to remember and cement the story of myself in my mind. I will likely reread these books in the years ahead to keep their lessons fresh.

7. Your Most Difficult Accomplishment

Remember your proudest moment? It likely stands out. A time when you did something you had no idea you could do. A time when you worked harder than usual and demonstrated to yourself that you can do hard things. These memories are important inspirations for future endeavors.

8. The Funniest Thing You Ever Heard or Saw

In my mind, laughter is one of the strangest but most wonderful aspects of being a human. Why does it feel so good? I try to maintain a mental list of the funniest moments of my life—it’s often great material for reliving these moments with friends.

9. A Bonding Conversation

Ultimately, life is about love and relationships. Those friendships are often forged in the fire of shared experiences and rich conversations. I still like to think about the long, rambling conversations in my college dorm room and take a moment to be grateful I have those memories to look back on.