A personal trainer is a fitness professional involved in exercise prescription and instruction. They motivate clients by setting goals and providing feedback and accountability to clients. Trainers also measure their client's strengths and weaknesses with fitness assessments. These fitness assessments may also be performed before and after an exercise program to measure their client's improvements in physical fitness. They may also educate their clients in many other aspects of wellness besides exercise, including general health and nutrition guidelines. Qualified personal trainers recognize their own areas of expertise. If a trainer suspects that one of his or her clients has a medical condition that could prevent the client from safe participation in an exercise program, they must refer the client to the proper health professional for prior clearance.