Off the top of my head I can't think of anything. But I know I will, so I'm going to be thinking about it today.
Did you think of something straight away?
I wish there was something I wanted to do, even if risk was an element in it. I'm feeling a bit annoyed with myself that I can't think of anything I want to do. I'm still thinking........
I'ld wonder whether the definition of "could not fail" is in the sense that you physically cannot fail (even if you tried) or whether failing is possible but undesirable... but that's just me.