If at first you don't succeed, skydiving is not for you.
The quote "If at first you don't succeed, skydiving is not for you" humorously suggests that some activities, particularly those that involve a high level of risk and danger like skydiving, require a certain degree of immediate success and competence. Unlike many pursuits in life where persistence and trying again are encouraged, skydiving is not forgiving; failure in this context can have serious consequences. Thus, the quote playfully implies that if one struggles to succeed in a critically important task, it might be best to avoid activities that involve life-or-death stakes. It highlights the importance of suitability and skill in high-risk scenarios.