Anyone can feel bad during parts of their life. Some people suffer from such feelings to a greater extent than others. There can be many reasons for this, and they may vary over time. It could be that we experience the serious illness or death of a close friend or family member. But it could also be due to the fact that we feel alone or inadequate.
There are a number of things you can do to try to feel better again. A good start is to take care of your basic needs such as food, sleep, physical activity and the need to be around other people or animals. If you are feeling bad then it is easy to become careless about satisfying your own important needs, in which case you run the risk of ending up in a downward spiral.
However, sometimes it is not enough to simply eat right, sleep well and exercise - sometimes you may also need professional help, in other words, someone you can go and talk to, or some form of medication.