Thimbles protect your fingers from pointy needles. Thimbles are made of leather, silicone, metal or plastic for the most part. Sizes are small, medium, large or they are sized numerically. Most thimbles are shaped to fit fingers but the main task is protecting your finger and helping to push the needles through your project. You might find the small circle leather and silicone-type thimbles easier to use than a fingertip glove type thimble.
If you find it uncomfortable to use a thimble, you might try wearing a thimble all day. Let yourself get used to the feeling of having it on and when you come to work on your project it becomes easier to use without thinking about it.