Hello. Based on the history you have given I am assuming that, you are a target oriented person, who belives that each and every second of our life should be accountable to something and it should serve the purpose and it should productive, all this things really sounds good but in reality every human being will day dream at some point of the time every day atleast for few seconds, which is a natural human instinct of hoping for something in their life. Also a day dream actually shows that you have a active brain. The only solution here is to develop focus on the work you do, so do daily meditation, pranayama, yoga and go for morning walks and try to engage in hobbies which makes you happy. Which helps you to get some concentration which you need. If you are still concerned kindly consult a psychiatrist for further queries.