How to design a fitness program for middle-aged and elderly people with poor physical fitness?

A few years ago, my grandmother went to the hospital many times because of poor health, in fact, it is not love the problem of physical exercise, and then the doctor's orders many times, finally willing to go downstairs, and now my grandfather every day to take her to the park to play taijiquan, with fitness and prolonged life, to prevent chronic diseases have a better effect, it is very suitable for older people in a kind of exercise program. First of all, when you play taijiquan, you pay full attention and concentrate highly. The eyes follow the hands, the steps change with the body, the movements are smooth, coherent, steady and coordinated, and the movement is quiet. Favorable to the rest of the brain; secondly, it helps to slow down the decline of muscle power, maintain and improve the flexibility and mobility of joints.