My grandparents are 70 years old. Is it very old? I don't have many years to live.

Your grandparents are over 70 years old. Not very old. And they are healthy and will live to be eighty or ninety years old. Because the average life expectancy in China is now 76 years, centenarians in many places are nothing new. We are surrounded by old people in their eighties and nineties. With the improvement of living conditions and the progress of medicine, people's life expectancy will increase. So you don't need to worry that your grandparents won't live for a few years. They will be healthy and long-lived old people.