That luck can range from finding dry wood to an old shelter to garbage washed up on shore to, as happened on Baffin Island, to throwing a hook and line into the water on the spur of the moment and catching three fish.
The same applies to trial work. In order to succeed in trial you must first be prepared. You have to know your case inside and out. You have to know where you're trying to go. You must also walk into that courtroom with the attitude that your story is going to prevail. In the words of Coach Tony D'Amato in Any Given Sunday, you have to see it, then do it. You have to have the courage to announce ready at docket call. You also have to have a bit of luck on your side. It can be anything from witnesses that don't show up to witnesses who, once caught in a lie, refuse to deviate from it.
Now you can't manufacture luck - just like you can't coach speed - but you can put yourself into position to benefit from it by being prepared and having the attitude that you can't lose.