Anxiety is excessive worry over a variety of problems for a prolonged period of time unique to each individual. It is the most common mental health issue that the general population deals with and is rooted in a deeper fear of the unknown or what might/could happen. People who don't deal with anxiety as an ongoing issue struggle to see how paralyzing and intense it can feel for the one it plagues.
This fear of uncertainty manifests itself in cognitive distortions such as catastrophizing, exaggerated expectations and black and white thinking patterns that leave little to no room for flexibility of possible outcomes. While the initial symptoms of anxiety begin in our thoughts / emotions, extended periods of anxiety that are not dealt with can result in physiological symptoms such as tingling of the skin, random muscle spasms/twitches, sleep problems, sweating, clammy/cold skin, or paralyzing fear that results in an inability to move or make decisions.
Precipitating factors for anxiety might be a specific event, stressful situation, distorted way of thinking, unhealthy belief systems, or dysfunctional coping patterns we've learned from others. Sometimes finding out "why" we are anxious is not so easy because it requires digging through our inner-self and being honest with what is really bothering us. It often helps to talk to a counsellor to help us draw out our fears and learn how to cope/manage/ heal from them more effectively.
An effective form of counselling for anxiety is cognitive-behavioural therapy. CBT teaches you how your thoughts, feelings, and behaviours work together. A goal of CBT is to identify and change the unhelpful patterns of thinking that feed anxious thoughts. Over time and through active practice, people struggling with anxiety can begin to take control of it. It is a very manageable problem to deal with even if you feel presently hopeless while you're enduring it.