Read Chapters and power points twice! Once out loud. I know it sounds crazy but, it really helps! Don't just highlight information. Take actual notes and read these a couple times. Being exposed to the information several times helps you remember. Also, when studying certain disease processes and conditions, think of people you know suffering from these or stories your instructors told. This also helps a lot!!! Good luck!
Do you know what's making you feel defeated and tired?
If it's the volume of information, you may want to review your study skills and see if you can find some new ones.
If the information is boring, maybe you're not cut out for med-surg. Learn it well - it's an excellent and irreplaceable basis for all kinds of nursing - and remember you're not stuck there.
If you're physically tired, well - nursing school is exhausting. Don't neglect your self care - eat properly, including treats; sleep enough, play enough, get physical exercise.
Does your school facilitate small groups for clinical work? Can you debrief with your colleagues?