It's all about your thoughts
All situations are temporary. Whether you believe this is a big deal or it's not a big deal, you are right. Your mind is the most powerful thing that you possess. It can make you feel great or awful depending on the thoughts you choose to think. Use it to calm yourself down and not make yourself more anxious or stressed. Think of a time when you were really calm and totally relaxed. Close your eyes and imagine yourself back there in that moment. Concentrate on breathing in through your nose and out through your mouth very slowly.
You have survived all of the difficult situations in your past
You might think that this stressful situation or episode is something that you will never be able to get over. Remember how many times you thought that in the past and remind yourself how you have moved on and now those situations aren't even important anymore. Time is the biggest healer and eases most pain or trauma. This situation will not be a big deal this time next year so don't allow yourself to get overwhelmed by it now.
Focus on what's important
We allow ourselves to stress about things that we know aren't really that big a deal but we get caught up in the drama of it all and one negative thought leads to the next. Ask yourself 'what is more important - blowing this out of all proportion, or getting over it right now and moving on?' Not every situation is going to be as easy as just "getting over it" but ask yourself how important the situation is in the grand scheme of life. If it doesn't effect you long term in a negative way then don't allow it to rent space in your brain. Focus on thinking more positive thoughts even if they are about a completely separate situation and soon your stressful situation will feel halved.
There is no wrong decision
If you are caught between making a decision based on the pros and cons of the choices you are faced with then there usually is no wrong decision. Go with your gut. When we overthink things we stress ourselves out and it builds bigger and bigger negative emotions. One negative thought leads to another and soon we are tumbling down a steep path of negativity which is very difficult to climb back up. Try to look at the options from both sides then pick a side and stick to it. It may not look like it was the right decision in 10 years time but it is the right decision for now.
Trust in the universe
This is probably the most difficult or easiest thing to do depending on how you look at it. It took me a long time to understand and trust how the law of the universe/law of attraction works but now I have had so much proof and I've seen it working time and time again I have no doubt in my mind that you can attract happiness, success or anything else you choose to attract. Similarly, you can attract stress and negativity by the way you think and the relationships you conduct with others. Ask yourself what you want to attract and surround yourself with those thoughts. If you allow stressful situations to get on top of you another stressful situation will manifest just around the corner. Learn to trust in the universe that positive things are coming your way and be really open to the idea. You will be amazed at the results!