I created Less Doing as a way of dealing with the stresses that were aggravating my Crohn's Disease. Everyone has stress in the life in one form or another and often times it can be a very useful force to motivate you towards a goal. When stress becomes chronic and spins out of control, you're mind and eventually your body will crack under the pressure. While I do recommend yoga, meditation and heart rate variability training as excellent methods for hacking your stress, the ultimate solution is the entire Less Doing framework of optimizing, automating, and outsourcing everything in your life.
When I initially explain this to people, many of them are surprised that a productivity system can help with their stress but it does for a very simple reason. It trains you to get into the mode of problem solving and constant progress. I believe that if you get into the habit of constantly looking for ways to optimize the things you do, become familiar with methods of automations so you can set and forget things, and gaining an awareness of the kinds of things you can outsource completely, then you will always know that a solution exists.
A lot of stress comes from feelings of overwhelm, but if you really think about it, stress comes down to feelings of helplessness. If you know what you need to do or even an inkling of how you will accomplish it, then you regain some control of the situation and the stress will become a motivator rather than a detractor. Just by knowing the pathways at your disposal, you will be better equipped to handle any problem or "emergency" that comes your way.