Greetings Mr. lybrate-user
I appreciate your effort that you were able to think about yourself could realize that something is not right. So as you mentioned that most of the time you think about your past and future. One question: Is it helping you out in some way or the other? Second question: what is the fear
and sadness all about? Think about it and analyze how can you find a solution for your sadness and fear, is the fear or sadness even valid or is it invalid or unnecessary thoughts of yours. Sometimes, we as humans like to fantasize or visualize or rather like to live our sadness or fear for a while and we try to gain something out of it. You need to think objectively and rationally that are you getting something from it, if no then you have to bring a control over your thoughts. Our mind may take us anywhere or may let us think whatever we wish to think or visualize but it is in our hand, the capacity to bring our mind back to the present and think and rethink that "what am I doing in the present, Am I simply
wasting time in unnecessary thoughts which will take me nowhere?
It is very important that the moment you get irrelevant thoughts you have to tell yourself that you have more urgent things to think and work upon. See this does not mean introspection is bad, rather I told you that its good that you could think about what you are experiencing these days.
But thinking too much past and future is simply going to ruin your future and moreover you can't change your past also.
It would be better if you can generate your will power all over again to truly fight with your thoughts and focus on present things as only present actions are going to decide your future, so rather than thinking too much about it, it is better you start doing it.
And once you start focusing on your present, it will be visible in your actions and your anxiety
will surely subside.