It's fun and easier than you think!
Sit for a moment and look around the room. Just notice the things you see.
Write or type a list of these things. If you see a pencil, and that reminds you of your favorite math teacher, or a tree, just let your thought flow down a river of words.
Start with 15 things. Imagine what you life would be like without the chair you are sitting on (or any chair), or without your shoes. Think about what these things give in your life. Now you can be grateful.
Take time throughout the day to notice little things you could put on your list. The gratitude grows, and it can change your entire outlook.
Good work! I love recieving gratitude lists!