A lot of people are unsure as to what to include in a bucket list, so they decide to put it off until they're crystal clear on exactly what they want. Don't allow performance anxiety to stop you from creating your bucket list. Start by creating a preliminary rough draft; you can always add, delete, or modify as you go along.
You're going to create your list by having an individual brainstorming session. Set your kitchen timer to go off in forty-five minutes and find a place where you won't be interrupted. Play Baroque music in the background, if you have it. Baroque music, such as "The Four Seasons" by Antonio Vivaldi and Pachbel's "Cannon" have been shown to slow brainwaves down to the Alpha range, the brain frequency which has been linked to increased creativity.
Do not criticize or evaluate what you write down during the brainstorming process: you're trying to open yourself up to possibilities. Write down whatever comes into your head, it doesn't matter how wildly impractical the idea seems. Basically, you're going to have to quiet your internal critic, that little voice in your head that might be saying: "You can't do that"; "That's silly"; "I can't afford that." Push the limit on what you currently think is possible for you and think outside the boundaries of your current life.
Don't stop at 100; write down as many things as come to your mind. Later you can sift through the list you created and narrow it down to 100.