Lay flat on your back, close your eyes and take a deep breath in through your nose, hold it for 10 seconds, then breathe out through your mouth. Keep trying it. It can take a little while to work but it does work a lot of the time. Tell yourself you are not going to die. what has caused the panic attack?
But you have plenty of years, and decades before you will die. Hopefully one day you will live to be in your 80s and 90s and just pass away peacefully in your sleep. Many people die that way. And even when we pass, we do not die. We live in others, we never really leave. That's the way I see it anyway!