For me some jumps just aren't constructed right, and you could hurt yourself. That said nothing's worse than not going hard enough and landing on the lip.
Get yourself psyched up for it, hit it hard, and tell yourself you're going to land it. Even if you don't, landing funny on the down ramp doesn't hurt much.
Now I need to take my own advice cause I'm a pussy when I'm staring at a launch ramp that looks like a wall!