Why boring???

Almost every class, students will do their presentation on a particular topic. And nearly all the presentation having the same response from the students. What response? Sleepy and boring! When the presenter scroll down the next slide, they will hope to see the wording "Thank you!" or "The End". If they see not their wanted slide, then they will ask when the presentation will end and how many remaining slides to go? Not only the students' presentation will have this type of response, even my presentation also having the same problem. Is that my lecture so boring? How to improve it? Purely theory, students will feel boring, calculation pulak, students will afraid to do it coz they don't like figures. Then how?