I find myself coming back again and again to this wonderful David Foster Wallace speech (~20 mins) on how to deal with existential angst, that I found a few months ago. I recommend you listen to it here while reading it here.
Summarizing or quoting here would be a disservice to the original so I am going to refrain from doing that. If you like what you hear and want to know more about DFW I recommend watching The End of the Tour.