I want the people I care about to doubt me, underestimate me, and be sure that I will fail. It's the best motivation for my success and it drives me more than pretty much anything else.
Because of the way doubt fuels me, I doubt most the people who I want most to succeed because I know how it feels. I believe that my doubt will be a great motivator to their success (if they know I am doubting them and they care about my opinion).
It's a loving sort of doubt, not the doubt expressed by people who want you to fail because of insecurities. This is an empowering doubt meant to help push someone to the next level and then shove it in my face.
Years ago I loved when people complimented me in various ways, but these days, I prefer the people who express doubt and arrogantly proclaim that I will be a failure. The compliments drove me to get fat and lazy, the doubt and arrogance drive me to work harder and ensure that I'll be shoveling dirt back in their faces as the years move on.
P.S. today my wife and I lost a dear grandmother on her side of the family. Death is always a sobering reminder of the fleeting nature of life. Take nothing for granted and do your best today as if it's your last.