Why do I feel twice my age ... and I don't think I have many years to live.

I don't know why you feel this way. Is the work pressure great? Have you experienced anything? Did you realize the hardships of the world too early? Suddenly I feel a lot older. Life is not easy for everyone. Maybe you will face more problems than others. It may cost you too much heart and energy. Makes you feel particularly tired. It will give you an illusion that your psychological age does not match your actual age. Try to relax yourself. Try to learn to decompress. Learn to enjoy life. Don't just rush, but also try to stop, learn to rest yourself and let your mind have a rest stop, understand?