Anything that threatens you with failure will sharply escalate your suffering. As with everything, there's an offset to pain and struggle. If you can cope, you gain tenacity and perseverance. No one succeeds in business without employing persistence to a greater extent than others. Without persistence you have no chance of achieving lofty goals.
Persistence is the single characteristic found universally among all successful entrepreneurs.
As Ray Croc pointed out, talent, education, and brain power amount to little without persistence. With every bout of pain comes growth. The anxiety you suffer enhances your spirit of faith, sharpens your wits, improves your ability to innovate, eliminates procrastination and gives you a more experienced level of decision making. It also forces you to develop new and better ways of marketing. Innovation and marketing are the most important functions of the entrepreneur.