Do you masturbate when you are sexually excited or you just do it for the sake of it.? A detail explanation of your problem would be helpful for us to comment on ya problem. Masturbating doesn't cause any harm by the way. Loss in pleasure might be if you are doing it just for the heck of it. Decreased erection if it is there can be due to a number of reasons for which you have to see a doctor. Reduce your weight do excercise and have a healthy lifestyle. The less cum and thin in viscosity can be improved by taking excessive fluids. Give gap between your masturbation sessions and the thickness will improve automatically. For other questions please visit a doctor.