A personal trainer is an individual certified to have a varying degree of knowledge of general fitness 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.