Don't freak out.
I'm re-reading a favorite book of mine; it's one of the only books I've read more than once by choice (as an English teacher one reads certain books over and over and over, which is nice). Buddhism Without Beliefs by Stephen Batchelor is a small book and in a simple way gets to the heart of everything in just a few words. Every time I've ever picked it up, it seems to support what ever is going on in my life at that moment.
Anyway, back to death meditation. Each chapter talks about one aspect of the path. This morning's chapter asks the question: Since death alone is certain and the time of death uncertain, what should I do? In thinking about that question, oh so early on a Saturday morning, I am aware that on one level I do keep this in mind as I live my life. I am also aware that I could think about this question more deeply on a daily basis to help me make decisions and to respond to occurrences in my everyday life. Meditating on death brings me down to (or up to?) the reality of existing. Getting to that level, makes me fearless...and content.