Truss rod adjustments for me, it's the one thing I don't have confidence in doing.
Although, the most stressful moment of my life was when my band was supposed to be onstage in 5 minutes and my mate says to me "Baz, I need to tune my guitar, can I borrow your tuner?"
Not so bad, right? But he has an Edge III and has zero knowledge of floating trems. I broke a sweat trying to get that thing in tune.