Your personality was pretty much set in stone by age 13. Focus on building self-confidence and righteousness. Eliminate Self-consciousness and doubt.
When I was in 5th and 6th grade, I was confident and righteous. I would stand up for myself and others. I would do what needed to be done, and I was sure of my actions.
When I was in 7th and 8th grade, I was self-conscious, fearful, unable to take action (unless it was on the field/court, where I had no problem)
I don't know what happened in-between 6th and 7th grade, but I need to always be my 6th grader. Not my 7th grader.
Be confident! Be righteous!
Now, as a grown man in his 40s, I struggle with boldness and confidence. I know enough to know that I don't really know anything, and that the action I'm taking is not the correct one, which makes it hard to be bold or confident. But the funny thing is that the boldness and confidence is what eventually makes it the correct action.