I have bad anxiety like extremely bad and I need to know what to do to fix it

Anxiety, like all emotions, has a purpose. The flight or fight response is a survival instinct that creates a physiological response to perceived threat or harm. Our ancient ancestors used this instinct for survival from dangerous predators and other physical threats. In modern times, we do not experience many of the threats that our ancestors did, but the flight or fight response is still quite powerful and often could be viewed as a 'faulty alarm system' when triggered by perceived harm.

When addressing symptoms of anxiety and depression, it is important to distinguish between things you can and cannot control. If you are worrying about things that you cannot control (others' thoughts, feelings, decisions, behavior), it is helpful to identify what you can control  (your own thoughts, feelings, decisions, behavior, self-care) and utilize your time and energy to focus on that. This shift often provides a sense of empowerment and encourages a more positive outlook on life. 

If you are worrying about things that could possibly or are unlikely to happen. I suggest challenging your anxious thoughts with evidence. Many times, we make assumptions or create stories in our heads of what will happen or what we 'feel' will happen without really looking at the facts. I often assign homework in the form of worksheets to practice challenging negative or anxious thoughts and replacing them with rational thoughts to help make a situation more manageable. Another approach I recommend is to identify the worst possible outcome, the best possible outcome, and the likely outcome, which promotes more rational thinking and less worry about 'what ifs.'

It can also be helpful to learn and practice relaxation exercises to manage anxiety, particularly focusing on the physiological effects it has on the body. Deep breathing and progressive muscle relaxation are two of the most common techniques that many people find helpful to calm themselves down.

Mindfulness if another excellent approach for reducing symptoms of anxiety and depression. Mindfulness has been defined as nonjudgmental awareness of our thoughts and feelings. When we spend too much time in our heads thinking about the past or the future, we are not experiencing the present moment, which is what we can control. There are various exercises available to practice mindfulness, one of which is using the five senses to identify things you can see, hear, touch, smell and taste. 

There are many things in life that we do not have control, but the one thing over which we do have control is ourselves, and there are many ways to exercise this control to benefit our mental and emotional health.