I had bypass heart surgery in 2012 and know how much your sternum can hurt and how limiting that is. I hope you have some pain medication on board for when you need it. I have IBS-M and know all about stress. I have had the best success though, over time, with incorporating the IBS into my life so it isn't separate but part of it. It simply is what I do and how I am at this point. Those mental gymnastics aside, any stress makes my rectum seize up and it feels like it has turned inside out. I have no choice but to ride that out. I try my best to work through stressful situations. Mental health therapy and meditation have helped. Good luck with your sternum-I am sure it will heal and perhaps your IBS will abate.