If you ever stop being nervous, quit.
As I approach my seminal 100th jump, the jump widely considered to separate the casual jumper, the dabbler or the mid-life crisis thrillboy from serious skydivers, I am still consistently having butterflies on the ride to altitude. I know and have experienced how safe the equipment is. I am familiar with all the procedures and I am proficient in all the aspects of safe jumping but I can't shake that feeling in my gizzard each time the plane lifts off.
Recently, I approached the most experienced jumper I know and asked if this was normal.
"I always get butterflies on the ride up," he told me. "If you ever stop getting nervous, quit."
This man, who I consider something of a mentor, has fifty skydives for every one of mine. He has a master rigging certificate and an AFF Evaluator rating, two of the most difficult certifications in the sport. He's been jumping for longer than I have been alive, starting out with military surplus gear and borrowed football helmets in the mid-seventies. He still gets nervous on the climb to altitude.
His point was two-fold, first, that we do something that would be, if not for our equipment, our training and our wits, outright suicidal. When you stop worrying about the consequences of failure, you've begun to believe that those three things are infallible; they are not. Forgetting this can be fatal.
More broadly, though, anything worth doing should challenge you, thrill you and, yes, scare you. Trepidation, whether fear for life or fear of failure, should accompany any worthwhile endeavor. If it does not, you've ceased to grow and should move on to something else before your actions become rote, before you get bored, sloppy and stupid.