It depends on what your goal is. If you simply lose weight, you should take three months as a stage and exercise 3~4 times a week. If you gain muscle, three or four times a week, plus diet, three meals and so on. If it is rehabilitation training, I suggest you listen to what the professional personal trainer has to say. But many personal trainers in the gym are not very qualified, so you should prepare some professional questions to ask your trainer. If you think it's ok and trustworthy, then practice with ta again!