Think about your self-talk and write down negative things you say to yourself.
For example, I'm not good at anything.
Judge your thoughts to see if there is any evidence that this is true.
For example, I can cook the best chocolate chip cookies. I get good grades in Math, I am great at Sodoku puzzles. You are good at three things (most likely more) so the statement, I'm not good at anything, is not true.
Replace the negative thought with a more positive one.
Next time you're tempted to say, I'm not good at anything, say something like I'm not great at spelling but I'm getting better.
All the best!