Unmotivated because of thoughts!?

Going into my teenage years i started getting very lost in my thoughts and kind of created a world of my own chaos. I became extremely morbid, always thinking about my death. Went to psychiatrists and doctors - the whole deal. Anytime I try to learn or do something i get this thought in my head..kind of like this.."theres no point in finishing or starting anything because it all leads to nothing" Im sure most of the population can byp that thought and continue but it's something that really pisses me off!!! i'll be really interested in something, reading or learning and i get this thought and it makes it feel pointless to work on something (myself) that will end in a matter of time. maybe somethign i'll learn in time. and no, this is not because of someones death or suicide. It's just this thought that leaves a pit in my stomach all the time and it's been in my life since I can remember