Note that even with no recent stresses you could still be in a high risk group just based on those things in your life that weaken your stress resistance. The exact nature of the change in health is highly individual and will probably involve your weakest link, no matter how healthy you may think you are.
For example, some people are prone to heart disorders, ulcers, colitis, asthma, recurring infections, kidney or liver disorders and even cancer.
The ability to cope can also be influenced by the individual's perception of his skill level or ability to perform. Even if someone is fully capable of carrying out a certain task, if he perceives he cannot cope this will greatly affect his stress levels and thus adversely affect his performance. What one individual is capable of absorbing/performing is not an indication of another's capacity.