Anxiety seems to plague every person alive, but some may struggle more than others. I've experienced anxiety attacks and generalized anxiety from both perspectives: the one struggling, and the one watching their friend struggle. From this, I've learned a few lessons about caring for someone with anxiety.
1. Have conversations about their anxiety.
Ultimately, each person responds to anxiety in a different way. The most helpful thing you can do is to have open conversations about what triggers their anxiety, what they usually do to deal with it, and how you can help in a way that's best for them. Be careful to not be all talk but no walk. Practice active listening in these conversations and put what you learn into action.
2. Be in tune with their indications of anxiety and help them find a safe space when they feel overwhelmed.
By having the aforementioned conversations, you'll know which kinds of situations cause your friend anxiety. When you're in those situations, pay special attention to your friend, offering your help and a way out. It may be best to sometimes avoid those situations altogether. I have a friend who can feel overwhelmed in crowded areas, so when we were on campus, we would avoid the Student Union as a place to hang out.
3. Be patient.
You'll find that an anxious person is unable to do a lot of things: order food, make phone calls, text back promptly, etc. Don't rush them. Just wait. My friend and I can both tend to feel overwhelmed by text messages, and we've come to a mutual understanding of not expecting the other to respond right away. Sometimes we do, and sometimes it takes a few days, but sometimes it can take weeks, even months. We've talked about it and constantly reassure the other that it's okay to take the time needed to respond. From being patient and having these open conversations, we know that no matter how long it takes to respond to a text message, a lack of response does not mean we're no longer good friends.
4. Praise their accomplishments.
Even the things that seem small can be a big deal for someone struggling with anxiety. If they hate talking on the phone and yet call their doctor to make an appointment (even if they put it off for weeks), tell them sincerely that you're proud of them. Punishing behavior you don't want to see is far less effective than rewarding the behavior you do want to see. So instead of telling them to just call because it's not a big deal, praise them when they finally are able to do it.
5.Help them through their anxiety attacks using breathing and grounding techniques.
Each person's anxiety attack looks different. For some, it may be crying, but others may experience intense nausea, paralyzing fear, etc. While it's good to know what is emotionally causing the anxiety attack, talking about the cause may result in more anxiety. It can be most helpful to deal with the physical responses first.
Anxiety triggers the amygdala and one's fight or flight response, resulting in a racing heart and other symptoms of an anxiety attack. The body needs to be calmed down before you can deal with the emotion of the anxiety attack. Help your friend using the 4-7-8 breathing technique: breathe in for 4 seconds, hold for 7, and breathe out for 8. It will slow down the heart-rate. Do this however many times is necessary.
Another technique I've heard of (but haven't personally used) is the grounding technique where you look around and find 5 things you can see, 4 things you can touch, 3 things you can hear, 2 things you can smell, and 1 thing you can taste. An anxiety attack is mental and emotional. Getting grounded in the physical reality helps when one feels out of control of their surroundings.
6. Don't tell them that they have nothing to be anxious about.
Whatever your good intentions, this will sound more like a rebuke than an encouragement. Belittling someone's worries is a sure way to be shut out. If they don't feel that you emotionally support them, they won't open up to you about future episodes. Instead, share truth. I personally prefer 1 Peter 5:7—
"Cast all your anxiety on him because he cares for you" (NIV).
Remind them of the Lord's heart portrayed here rather than shoving the command down their throats. Being told you shouldn't be doing something just evokes guilt, whereas being reminded of promises and what you can have will give a sense of peace. It's not "Stop, you shouldn't be feeling anxious right now," but "The Lord cares about you and will be faithful to work all things out for your good; you can rest." It's a subtle shift, but an important one.
More than likely, telling someone they don't need to be anxious is said out of a heart to help them see that their fears might be unfounded. But there is a difference between telling someone to just not be anxious and walking them through the logical sequence of events.
7. Walk them through their fear logically.
Anxiety and fear is often irrational. However, irrational is not invalid. Just because what someone is feeling doesn't make logical sense does not mean it doesn't matter; it does, and it's the most real thing for them in that moment. But because fears are irrational, walking them through the situation logically could help.
Say your friend is anxious about a job interview. Asking "What's the worst that can happen?" will help them by voicing their fears.
"I'll say the wrong thing."
"And then what?"
"They won't like me and I won't get the job."
"And then what?"
"I'll have to find another job, but I'll mess that interview up as well and I'll never find a job and I won't have a source of income and I'll go into debt and be homeless or have to live with my parents—"
And then the spiraling happens, and it's your job to remind them of the unlikelihood of all of those things happening.
"Or you will find another job. Or you won't say the wrong thing and the interview will go great. Or even if you do say the wrong thing, they'll still like you and you'll still get the job."
Anxiety is focusing on the worst case scenario. Help them switch the hauntingly negative "What ifs?" to more positive "What if this works out? What if all my hard work pays off?"
8. Remember that you cannot and should not be their only source of support.
Encourage them to see a professional who is better equipped at helping them than you. At UCF at least, any student can go to CAPS (Counseling And Psychological Services) to see a therapist for free. When I was a student at UCF, I utilized these services and it helped immensely. Encourage your friend to go, and keep conversations about going to therapy positive. Ask them how it's going without intruding, and remind them how proud of them you are for seeking help.
Everything listed here is hopefully general and basic enough so that it can be applied and/or modified for each person with anxiety. Maybe the breathing technique won't help your friend but the grounding one will, and vice versa. Understand your friend and get involved in doing what's best for them.