It could be many things. It could be from slouching or sitting in a way that is causing the diaphragm to be compressed. Do not try to over straighten, just think of relaxing the muscles and allowing yourself to fall into a natural position. It could be injury from working out and doing crunches or other movements. It could be a stomach ulcer.
Another option is to blanch green beans quickly. Blanch your green beans by boiling them for 3 or 4 minutes. This removes the skin of your green beans. You want your beans to be somewhat tender, yet have a little bit of crispness to them. Determine the crispness, by how long you boil them.
How to Cook Green Beans in the Microwave. Place green beans in a casserole dish with 2 tablespoons water. Microwave, covered, on 100 percent power (high) until crisp-tender, stirring once: - 8 to 12 minutes for whole or cut green beans. - 7 to 10 minutes for French-cut green beans. How to Steam Green Beans.