Being mentally fit means to be able to keep your mind and emotions in a good state. It has to do with your brain, psychological and social well being. Your mental state affect how to feel, think and act.
In our society today, we focus more on physical fitness and less on mental fitness. When one is mentally fit, life becomes a lot easier, you will be in charge of your mind and emotions, a good mental and physical health is needed for a complete healthy life.
There are a lot of people who are always focused on their physical health that they seem to forget that mental health is also very important. A healthy body will be able to do a lot of activities but a healthy mind can do so much more. Having a healthy mind means that you are able to deal with your feelings.
This means that you can recognize when you are having a bad day but you will do more so that you can have better days. The more that you are able to think clearly, the more that you can enjoy life and make decisions that will improve your current condition.