I had a similar mental block but eventually i got past it, just tell yourself that all these other people can fly in their dreams so i should be able too! Also wactch videos like this to help imagine what it would be like. and a question, have you been lucid and tried to fly? The main thing is though you have to truely believe or else it will not work. Tell yourself that this is what you really want, and its worth a shot to try. Hope i helped at least a little 
Check out Here on how to fly!