Everyone has episodes in their lives which could trigger stress responses or make existing problems worse. Some of us cope better than others, a fact which depends on many things about our biological makeup and what happens in our early lives.
Although one in four of us may one day have some sort of diagnosable mental health problem in our life-time, very few of us will have a serious mental illness. Even if both your parents have mental illness you are still much more likely not to have mental illness yourself than you are to have it.
If you are worried at any time that you may have symptoms it is sensible to go straight away to your GP. Starting treatment early can really help in terms of keeping you well and able to function normally. However, talking to someone who you trust about the feelings inside you can help to protect you.