Identify an area where you have more of a Growth Mindset, where you feel comfortable trying new things and believe you can improve your abilities. This could be an academic subject, a hobby, a sport, etc. With this area in mind, consider the following questions:
When did you first learn about it?
Was it something that adults around you did?
Were you encouraged to try it?
Do you remember what it felt like to not know how to do it?
Did you receive any guidance in learning it?
What feedback did you receive when you did it well?
What feedback did you receive when you didn't do it well?
Did you have friends or family members around you who were also interested in it?
Reflecting on your responses to the questions above, see if you can identify points when a different response to your efforts might have changed how you felt about continuing to learn in that area.
While it's possible for someone to learn about something on their own and become good at it without any outside encouragement, it's far more common to develop a Growth Mindset about a particular subject or activity for which we received some form of guidance and/or encouragement.
Because of this, assumptions about who will "naturally" be good at something can create a self-fulfilling prophecy:
Someone in your life assumes you will be good at something...
If you aren't already good at it, they encourage you to practice so that you can fulfill the potential they imagine you to have...
The experience of being encouraged and having someone believe you can become good at something makes it easier to persevere when you encounter challenges
You become good at the thing, and the person who encouraged you has their assumptions confirmed
The self-fulfilling prophecy can work in the other direction too. If someone assumes you will "naturally" be bad at something, any setbacks you experience as part of the learning process will look to that person like proof they were right about your potential.
And, of course, if we receive messages from the world around us indicating that we won't ever be good at something, why would we put time and effort into trying anyway?
As a TA, you can treat all students as though they have potential, even if they haven't realized it yet. That alone won't magically make them excel, but it is at least one less obstacle in their way.