We all want a long term solution that works as quick as possible...
Stress is built up energy... Energy must be directed.
Therefore, a releasing of it can be very easy.
For the quick release,... breathing as mentioned by a few here is a key way. However, what you do with your mind while you breathe in slowly through the nose and then out the mouth will help reprogram parts of your system. In the beginning, first few breathes, say to yourself in your mind while breathing in, "I am relaxed and at peace. Each time your breathe out say "this stress is no longer allowed in my body." Then as you proceed focus on the "I am relaxed" thought. While doing this focus on something pleasing to your eyes. There is much more to share but this will help in a big way.
Each small step we take each day is dependent upon the foundation we are working from.
Quite simply everything begins in the Brain. If the elements that are required in this amazing electronic switching station are not in play then we will have at best limited results in any changes we seek to implement. When we reverse engineer how Stress happens it is easier to see how to avoid it as well as how to undo it.
A well rounded process is essential. Diet, supplementation, movement, affirmations, are all an important part of effecting change. It is imperative for everyone to establish where they are.
May you find peace!