Why do I always feel anxious?

Being able to know you feel anxiety and write about it, is the first step to addressing and handling it!

Generally, anxiety is deep fear of not being able to handle what comes up in life. 

 Somehow the person was insufficiently nurtured and so felt  insecure when very young.

Usually the person had to fend on at least a psychological and emotional level for themselves before reaching an age when doing so would have been reasonable.

Their inner feeling of overwhelmed from when very young, hasn't faced the reality that the grown person is now capable, even if this takes some practice. 

Try asking yourself what you are afraid of and theorize how you would handle these situations as a grown person.

Also, sometimes anxiety comes from feeling lonely.  This loneliness is reminiscent of the loneliness that the grown person now, felt when being left to take care of situations as a child which were too difficult and complex for any child to address.