I am a professional worrier. I can ALWAYS find something to worry about, no matter how ridiculous it might be. 99.9% of the time, the things I worry about are not going to matter three years in the future.
One worry that will matter in the future is my health and the worry of having to deal with cancer again. That's not a worry I have all the time, but more often it happens at night when I'm having trouble sleeping, and I just start thinking of all the worst case scenarios. I suppose it is always in the back of my mind, but I try not to let it become the focus of my life.