I am going to die at the age of 21. I turn 21 in 3 weeks. What should I do? Please be logical.?

I have been having dreams about this since before the doctor told me I shouldn't expect to live past 21 when I was just 8 years old. I still have these dreams. The dreams are unrelated to what the doctor said, but it seems that it's going to be inevitable sometime within the next 10 months and I don't know what I should be doing. I just started freaking out recently and I feel like I'm being pretty irrational and inconsistent with what I say and do because of it.