I feel sad for no reasonMy mind aces

It is important to know that it is normal for a person in life to experience sudden situations that cause him / her a grief, but soon those feelings can end. if the cause has been tackled or after a period of time has passed on that accident, because people adapt sooner or later to the surrounding circumstances.
Sometimes a person could be exposed to a state of sadness and that sadness takes different forms, as a result the person may feel to cry or isolate, and this period may take long depending on the person him/herself and his /her ability to control the feelings and behaviors in times of stress wisely and rationally without any emotions controlling  him. 

Try to talk to yourself and search for the reasons that led you for that sudden state of sadness, there is no sadness without a reason even if it is simple, what you are going through is a simple state which you can control, but you have to get rid of the reason, so it does not develop to a state of depression.
You have to keep exercising and do relaxation exercises as well.
Sports and activities can release your tension, boost your self-confidence and abilities, thereby helping yourself to overcome feelings of sadness.
You also have to understand the nature of the situations that you are exposed to and understand them well, because your right and visible understanding of these situations is what will help you get rid of sad times.
Chang your daily routine, as you can practice different and new activities, doing the things that charge you with happiness and comfort, talking to someone you relax, go out on recreational trips