We each have a different tolerance for pain, so only you can answer that question. The fear of the unknown. When we are operating out of ignorance, we usually imagine the very worst possible scenario. It is up to you to ask questions, to educate yourself about the disease, and to move from the unknown to the known. Each of you can probably enlarge and expand this list, based on what is happening in your life.
Illness does create fears.
Discuss them with friends and family members. Force them out into the bright daylight. That alone will help put them into perspective. Seek out other people with arthritis and see if they have had the same fears. You may be surprised.