This might be one of the greatest secret I have ever kept and that I usually forget until I, well, until I remember about it again, and whenever I do, I feel like everything is going to be okay.
As I sometimes deal with anxiety, this helps me breathe in and out and remember I can do it.
Whenever you are overwhelmed, stressed and fear is making knots in your stomach, sit down and make a list of all the things that are giving you these sensations.
Most of the times there will not be more than 7 items on your list, but if they are, it is fine, great things take time.

Once your cause of stress is lied down on paper, attribute one day of the week to each of the items.
Afterward, you need to try to forget about all of them -since you will deal with later on- and focus on one each day.
7 days a week,
7 problems,
1 to be solved each day.
Whether it is emotional, practical, at school or at home: give yourself a day to think about it and know how you will deal with the problem or solve it.
When I am feeling anxious about school, I always take the time to make a list of all the things I have to do, separating every single task, and then I start and I do it.
When I am emotionally feeling stressed about a situation, I sit down and take the time to think what makes me feel so and why. Finding out why will help you search for solutions and understand yourself. If you understand why you are feeling this way, you are more likely to learn how to deal with your stress in situations alike.
Disclaimer: I am not a therapist, this is just a personal way to deal with anxiety and stress, and I thought I’d share it with you.