I would suggest you evaluate your diet and state of general health. Many people ask how to let go of anger, as if the problem is only psychological. But in fact, the problem could lie in the foods you eat. Bad foods promote bad health and cause health problems that make people angry. Good foods promote good health, such as good concentration, a strong memory and positive moods.
Sometimes all you need is a change in your diet to feel better instantly. Fruits and vegetables are packed with nutrients that boost energy levels and improve brain function, especially the part that is responsible for producing 5-hydroxytryptamine, the increase of which significantly elevates your mood.
Also, exercise more often. Regular exercise is known to make people feel more optimistic and bring out more positive emotions. Improvement in your diet and fitness is the best solution to your problem.