In more ways than one, anxiety is a battle. It can be a little battle, it can eat you alive. You have to learn a simple key (if the big picture is what is giving you anxiety): Take everything one step at a time.
I learned this, only this year. To remain calm when thinking about school. Only thinking about the assignment ahead of me. Only thinking of the conversation ahead of me. Make anxiety small by thinking small. Have and essay and 2 exams due in a week? do the essay, and then do the exams. Don't think of it all at once.
You think of anxiety big picture it will smother you. It will make you weep.
Easiest way to explain it in relevant terms is: If you have a room that is cluttered or dirty or a house that is dirty. Pick one room, or one corner. Clean/declutter it. Take a 5 minute break then take another room or corner. Slowly work your way around the room and rationalize it all. Don't look at it as one room, or you have to clean the whole house. That sparks cortisol flow and starts the stress reaction in your body.
Life is a series of steps, and battling anxiety should be a series of steps as well. Long series of steps but eventually you will get there.
You are human, you will feel stress, you will feel anxiety. But take it one step at a time, one minute at a time. Anxiety should begin to leave you. Also: remember to breathe deeply if you feel anxiety. Oxygen will help the body's natural reaction to get blood flow pumping and calm down the nerves. It will also clear your mind.