According to many students, introductory physics is difficult. We investigated what students believe makes physics difficult and what can be done to overcome these difficulties. Our investigation included an initial free-response survey given to approximately 1400 students in an introductory physics course and a second survey, which was given to approximately 400 students in another semester, distilled from the responses to the first survey. Our findings show that the conceptions of the students and faculty members were different in terms of difficulties that students encounter in a physics course. The perceptions of students and TAs were mostly the same. Both students and faculty members agreed that student-related factors, such as not studying more, have the most influence on students' success in physics.