Yes. You need to understand that your relationship with your attorney is a partnership. The attorney will need to be able to contact the client and receive prompt responses with any needed information. In addition, the value of the case is greatly impacted by the client's honesty and forthrightness. Insurance companies' lawyers love to argue that the Plaintiff is exaggerating their injuries or that the injury already existed.
The only way to combat this is to provide all information, good and bad, to your treating doctors and your attorney about your prior health history. Frequently, the client can create much bigger problems by trying to hide information, than any problem that could be caused by the information coming out. In short, be honest with your attorney and doctors, and follow their advice. Defense lawyers also like to argue that the Plaintiff should not recover because they failed to do what is in their best interests. If the doctor says that you should walk two miles per day, you should do it. If you don't you are hurting yourself, physically and financially.