Why am I CONSTANTLY thinking about my Grandparents dying ?? =*(?

I can understand that you feel this way, but....they are in their 60's and that isn't so old. Things change in your life, do you just feel like you will be alone when they are gone? Other people come into your life, like a partner and children. You are doing the right thing - appreciating them. No one can control the future, and they may have very long lives.